// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifdef UNSAFE_BUFFERS_BUILD
// TODO(crbug.com/40285824): Remove this and convert code to safer constructs.
#pragma allow_unsafe_buffers
#endif

#include "chrome/browser/themes/browser_theme_pack.h"

#include <limits.h>
#include <stddef.h>

#include <algorithm>
#include <array>
#include <limits>
#include <memory>
#include <optional>
#include <string_view>
#include <utility>

#include "base/containers/contains.h"
#include "base/containers/fixed_flat_set.h"
#include "base/containers/heap_array.h"
#include "base/containers/span.h"
#include "base/files/file.h"
#include "base/memory/ref_counted_memory.h"
#include "base/memory/scoped_refptr.h"
#include "base/metrics/histogram_macros.h"
#include "base/no_destructor.h"
#include "base/numerics/safe_conversions.h"
#include "base/strings/string_number_conversions.h"
#include "base/strings/string_util.h"
#include "base/strings/string_view_util.h"
#include "base/strings/utf_string_conversions.h"
#include "base/task/thread_pool.h"
#include "base/threading/thread_restrictions.h"
#include "build/build_config.h"
#include "chrome/browser/themes/theme_properties.h"
#include "chrome/browser/ui/color/chrome_color_id.h"
#include "chrome/browser/ui/frame/window_frame_util.h"
#include "chrome/common/extensions/manifest_handlers/theme_handler.h"
#include "chrome/common/themes/autogenerated_theme_util.h"
#include "chrome/grit/theme_resources.h"
#include "components/crx_file/id_util.h"
#include "content/public/browser/browser_thread.h"
#include "third_party/skia/include/core/SkCanvas.h"
#include "third_party/skia/include/core/SkColor.h"
#include "ui/base/resource/data_pack.h"
#include "ui/color/color_mixer.h"
#include "ui/color/color_provider.h"
#include "ui/color/color_recipe.h"
#include "ui/color/color_transform.h"
#include "ui/gfx/canvas.h"
#include "ui/gfx/codec/png_codec.h"
#include "ui/gfx/color_analysis.h"
#include "ui/gfx/color_palette.h"
#include "ui/gfx/color_utils.h"
#include "ui/gfx/geometry/size_conversions.h"
#include "ui/gfx/geometry/skia_conversions.h"
#include "ui/gfx/image/canvas_image_source.h"
#include "ui/gfx/image/image.h"
#include "ui/gfx/image/image_skia.h"
#include "ui/gfx/image/image_skia_operations.h"
#include "ui/gfx/image/image_skia_rep.h"

using content::BrowserThread;
using extensions::Extension;
using TP = ThemeProperties;

// Persistent constants for the main images that we need. These have the same
// names as their IDR_* counterparts but these values will always stay the
// same.
enum BrowserThemePack::PersistentID : int {
  kInvalid = -1,
  kFrame = 1,
  kFrameInactive = 2,
  kFrameIncognito = 3,
  kFrameIncognitoInactive = 4,
  kToolbar = 5,
  kTabBackground = 6,
  kTabBackgroundIncognito = 7,
  // kTabBackgroundV = 8, Deprecated and unused. Previously supported windows
  // vista aero glass theme.
  kNtpBackground = 9,
  kFrameOverlay = 10,
  kFrameOverlayInactive = 11,
  kButtonBackground = 12,
  kNtpAttribution = 13,
  kWindowControlBackground = 14,
  kTabBackgroundInactive = 15,
  kTabBackgroundIncognitoInactive = 16,
  kMaxValue = kTabBackgroundIncognitoInactive,
};

namespace {

using PRS = BrowserThemePack::PersistentID;

// The tallest tab height in any mode.
constexpr int kTallestTabHeight = 41;

// The tallest height above the tabs in any mode is 19 DIP.
constexpr int kTallestFrameHeight = kTallestTabHeight + 19;

// Version number of the current theme pack. We just throw out and rebuild
// theme packs that aren't int-equal to this. Increment this number if you
// changed default theme assets, if you need themes to recreate their generated
// images (which are cached), if you changed how missing values are
// generated, or if you changed any constants.
const int kThemePackVersion = 104;

// IDs that are in the DataPack won't clash with the positive integer
// uint16_t. kHeaderID should always have the maximum value because we want the
// "header" to be written last. That way we can detect whether the pack was
// successfully written and ignore and regenerate if it was only partially
// written (i.e. chrome crashed on a different thread while writing the pack).
const int kMaxID = 0x0000FFFF;  // Max unsigned 16-bit int.
const int kHeaderID = kMaxID - 1;
const int kTintsID = kMaxID - 2;
const int kColorsID = kMaxID - 3;
const int kDisplayPropertiesID = kMaxID - 4;
const int kSourceImagesID = kMaxID - 5;
const int kScaleFactorsID = kMaxID - 6;

struct PersistingImagesTable {
  // A non-changing integer ID meant to be saved in theme packs. This ID must
  // not change between versions of chrome.
  BrowserThemePack::PersistentID persistent_id;

  // The IDR that depends on the whims of GRIT and therefore changes whenever
  // someone adds a new resource.
  int idr_id;

  // String to check for when parsing theme manifests.
  const char* const key;
};

// IDR_* resource names change whenever new resources are added; use persistent
// IDs when storing to a cached pack.
constexpr PersistingImagesTable kPersistingImages[] = {
    {PRS::kFrame, IDR_THEME_FRAME, "theme_frame"},
    {PRS::kFrameInactive, IDR_THEME_FRAME_INACTIVE, "theme_frame_inactive"},
    {PRS::kFrameIncognito, IDR_THEME_FRAME_INCOGNITO, "theme_frame_incognito"},
    {PRS::kFrameIncognitoInactive, IDR_THEME_FRAME_INCOGNITO_INACTIVE,
     "theme_frame_incognito_inactive"},
    {PRS::kToolbar, IDR_THEME_TOOLBAR, "theme_toolbar"},
    {PRS::kTabBackground, IDR_THEME_TAB_BACKGROUND, "theme_tab_background"},
    {PRS::kTabBackgroundInactive, IDR_THEME_TAB_BACKGROUND_INACTIVE,
     "theme_tab_background_inactive"},
    {PRS::kTabBackgroundIncognito, IDR_THEME_TAB_BACKGROUND_INCOGNITO,
     "theme_tab_background_incognito"},
    {PRS::kTabBackgroundIncognitoInactive,
     IDR_THEME_TAB_BACKGROUND_INCOGNITO_INACTIVE,
     "theme_tab_background_incognito_inactive"},
    {PRS::kNtpBackground, IDR_THEME_NTP_BACKGROUND, "theme_ntp_background"},
    {PRS::kFrameOverlay, IDR_THEME_FRAME_OVERLAY, "theme_frame_overlay"},
    {PRS::kFrameOverlayInactive, IDR_THEME_FRAME_OVERLAY_INACTIVE,
     "theme_frame_overlay_inactive"},
    {PRS::kButtonBackground, IDR_THEME_BUTTON_BACKGROUND,
     "theme_button_background"},
    {PRS::kNtpAttribution, IDR_THEME_NTP_ATTRIBUTION, "theme_ntp_attribution"},
    {PRS::kWindowControlBackground, IDR_THEME_WINDOW_CONTROL_BACKGROUND,
     "theme_window_control_background"},

    // /!\ If you make any changes here, you must also increment
    // kThemePackVersion above, or else themes will display incorrectly.
};

BrowserThemePack::PersistentID GetPersistentIDByName(const std::string& key) {
  auto* it = std::ranges::find_if(kPersistingImages, [&](const auto& image) {
    return base::EqualsCaseInsensitiveASCII(key, image.key);
  });
  return it == std::end(kPersistingImages) ? PRS::kInvalid : it->persistent_id;
}

BrowserThemePack::PersistentID GetPersistentIDByIDR(int idr) {
  auto* it =
      std::ranges::find(kPersistingImages, idr, &PersistingImagesTable::idr_id);
  return it == std::end(kPersistingImages) ? PRS::kInvalid : it->persistent_id;
}

// Returns true if the scales in |input| match those in |expected|.
// The order must match as the index is used in determining the raw id.
bool InputScalesValid(std::string_view input,
                      base::span<ui::ResourceScaleFactor> expected) {
  if (input.size() != expected.size() * sizeof(float)) {
    return false;
  }
  auto scales = base::HeapArray<float>::WithSize(expected.size());
  base::as_writable_byte_span(base::allow_nonunique_obj, scales)
      .copy_from(base::as_byte_span(input));
  for (size_t index = 0; index < expected.size(); ++index) {
    if (scales[index] != ui::GetScaleForResourceScaleFactor(expected[index])) {
      return false;
    }
  }
  return true;
}

// Returns |scale_factors| as a string to be written to disk.
std::string GetResourceScaleFactorsAsString(
    base::span<const ui::ResourceScaleFactor> scale_factors) {
  auto scales = base::HeapArray<float>::WithSize(scale_factors.size());
  for (size_t i = 0; i < scale_factors.size(); ++i) {
    scales[i] = ui::GetScaleForResourceScaleFactor(scale_factors[i]);
  }
  return std::string(base::as_string_view(
      base::as_byte_span(base::allow_nonunique_obj, scales)));
}

struct StringToIntTable {
  const char* const key;
  TP::OverwritableByUserThemeProperty id;
};

// Strings used by themes to identify tints in the JSON.
const StringToIntTable kTintTable[] = {
    {"background_tab", TP::TINT_BACKGROUND_TAB},
    {"buttons", TP::TINT_BUTTONS},
    {"frame", TP::TINT_FRAME},
    {"frame_inactive", TP::TINT_FRAME_INACTIVE},
    {"frame_incognito", TP::TINT_FRAME_INCOGNITO},
    {"frame_incognito_inactive", TP::TINT_FRAME_INCOGNITO_INACTIVE},

    // /!\ If you make any changes here, you must also increment
    // kThemePackVersion above, or else themes will display incorrectly.
};
const size_t kTintTableLength = std::size(kTintTable);

// Strings used by themes to identify colors in the JSON.
constexpr StringToIntTable kOverwritableColorTable[] = {
    {"background_tab", TP::COLOR_TAB_BACKGROUND_INACTIVE_FRAME_ACTIVE},
    {"background_tab_inactive",
     TP::COLOR_TAB_BACKGROUND_INACTIVE_FRAME_INACTIVE},
    {"background_tab_incognito",
     TP::COLOR_TAB_BACKGROUND_INACTIVE_FRAME_ACTIVE_INCOGNITO},
    {"background_tab_incognito_inactive",
     TP::COLOR_TAB_BACKGROUND_INACTIVE_FRAME_INACTIVE_INCOGNITO},
    {"bookmark_text", TP::COLOR_BOOKMARK_TEXT},
    {"button_background", TP::COLOR_CONTROL_BUTTON_BACKGROUND},
    {"frame", TP::COLOR_FRAME_ACTIVE},
    {"frame_inactive", TP::COLOR_FRAME_INACTIVE},
    {"frame_incognito", TP::COLOR_FRAME_ACTIVE_INCOGNITO},
    {"frame_incognito_inactive", TP::COLOR_FRAME_INACTIVE_INCOGNITO},
    {"ntp_background", TP::COLOR_NTP_BACKGROUND},
    {"ntp_header", TP::COLOR_NTP_HEADER},
    {"ntp_link", TP::COLOR_NTP_LINK},
    {"ntp_text", TP::COLOR_NTP_TEXT},
    {"omnibox_background", TP::COLOR_OMNIBOX_BACKGROUND},
    {"omnibox_text", TP::COLOR_OMNIBOX_TEXT},
    {"tab_background_text", TP::COLOR_TAB_FOREGROUND_INACTIVE_FRAME_ACTIVE},
    {"tab_background_text_inactive",
     TP::COLOR_TAB_FOREGROUND_INACTIVE_FRAME_INACTIVE},
    {"tab_background_text_incognito",
     TP::COLOR_TAB_FOREGROUND_INACTIVE_FRAME_ACTIVE_INCOGNITO},
    {"tab_background_text_incognito_inactive",
     TP::COLOR_TAB_FOREGROUND_INACTIVE_FRAME_INACTIVE_INCOGNITO},
    {"tab_text", TP::COLOR_TAB_FOREGROUND_ACTIVE_FRAME_ACTIVE},
    {"toolbar", TP::COLOR_TOOLBAR},
    {"toolbar_button_icon", TP::COLOR_TOOLBAR_BUTTON_ICON},
    {"toolbar_text", TP::COLOR_TOOLBAR_TEXT},

    // /!\ If you make any changes here, you must also increment
    // kThemePackVersion above, or else themes will display incorrectly.
};
constexpr size_t kOverwritableColorTableLength =
    std::size(kOverwritableColorTable);

// Colors generated based on the theme, but not overwritable in the theme file.
constexpr int kNonOverwritableColorTable[] = {
    TP::COLOR_NTP_LOGO,
    TP::COLOR_NTP_SECTION_BORDER,
    TP::COLOR_TAB_FOREGROUND_ACTIVE_FRAME_INACTIVE,
    TP::COLOR_TAB_THROBBER_SPINNING,
    TP::COLOR_TAB_THROBBER_WAITING,
    TP::COLOR_TOOLBAR_BUTTON_ICON_HOVERED,
    TP::COLOR_TOOLBAR_BUTTON_ICON_PRESSED,
    TP::COLOR_WINDOW_CONTROL_BUTTON_BACKGROUND_ACTIVE,
    TP::COLOR_WINDOW_CONTROL_BUTTON_BACKGROUND_INACTIVE,
    TP::COLOR_WINDOW_CONTROL_BUTTON_BACKGROUND_INCOGNITO_ACTIVE,
    TP::COLOR_WINDOW_CONTROL_BUTTON_BACKGROUND_INCOGNITO_INACTIVE

    // /!\ If you make any changes here, you must also increment
    // kThemePackVersion above, or else themes will display incorrectly.
};
constexpr size_t kNonOverwritableColorTableLength =
    std::size(kNonOverwritableColorTable);

// The maximum number of colors we may need to store (includes ones that can be
// specified by the theme, and ones that we calculate but can't be specified).
constexpr size_t kColorsArrayLength =
    kOverwritableColorTableLength + kNonOverwritableColorTableLength;

// Strings used by themes to identify display properties keys in JSON.
const StringToIntTable kDisplayProperties[] = {
    {"ntp_background_alignment", TP::NTP_BACKGROUND_ALIGNMENT},
    {"ntp_background_repeat", TP::NTP_BACKGROUND_TILING},
    {"ntp_logo_alternate", TP::NTP_LOGO_ALTERNATE},

    // /!\ If you make any changes here, you must also increment
    // kThemePackVersion above, or else themes will display incorrectly.
};
const size_t kDisplayPropertiesSize = std::size(kDisplayProperties);

int GetIntForString(const std::string& key,
                    const StringToIntTable* table,
                    size_t table_length) {
  for (size_t i = 0; i < table_length; ++i) {
    if (base::EqualsCaseInsensitiveASCII(key, table[i].key)) {
      return table[i].id;
    }
  }

  return -1;
}

struct CropEntry {
  BrowserThemePack::PersistentID prs_id;

  // The maximum useful height of the image at |prs_id|.
  int max_height;
};

// The images which should be cropped before being saved to the data pack. The
// maximum heights are meant to be conservative as to give room for the UI to
// change without the maximum heights having to be modified.
// |kThemePackVersion| must be incremented if any of the maximum heights below
// are modified.
const struct CropEntry kImagesToCrop[] = {
    {PRS::kFrame, kTallestFrameHeight},
    {PRS::kFrameInactive, kTallestFrameHeight},
    {PRS::kFrameIncognito, kTallestFrameHeight},
    {PRS::kFrameIncognitoInactive, kTallestFrameHeight},
    {PRS::kFrameOverlay, kTallestFrameHeight},
    {PRS::kFrameOverlayInactive, kTallestFrameHeight},
    {PRS::kToolbar, 200},
    {PRS::kButtonBackground, 60},
    {PRS::kWindowControlBackground, 50},
};

// A list of images that don't need tinting or any other modification and can
// be byte-copied directly into the finished DataPack. This should contain the
// persistent IDs for all themeable image IDs that aren't in kFrameValues,
// kTabBackgroundMap or kImagesToCrop.
constexpr auto kPreloadIDs = std::to_array<BrowserThemePack::PersistentID>({
    PRS::kNtpBackground,
    PRS::kNtpAttribution,
});

// Returns a piece of memory with the contents of the file |path|.
scoped_refptr<base::RefCountedMemory> ReadFileData(const base::FilePath& path) {
  if (!path.empty()) {
    base::File file(path, base::File::FLAG_OPEN | base::File::FLAG_READ);
    if (file.IsValid()) {
      int64_t length = file.GetLength();
      if (length > 0 && length < INT_MAX) {
        int size = static_cast<int>(length);
        std::vector<unsigned char> raw_data;
        raw_data.resize(size);
        char* data = reinterpret_cast<char*>(&(raw_data.front()));
        if (file.ReadAtCurrentPos(data, size) == length) {
          return base::MakeRefCounted<base::RefCountedBytes>(
              std::move(raw_data));
        }
      }
    }
  }

  return nullptr;
}

// Computes a bitmap at one scale from a bitmap at a different scale.
SkBitmap CreateLowQualityResizedBitmap(
    const SkBitmap& source_bitmap,
    ui::ResourceScaleFactor source_scale_factor,
    ui::ResourceScaleFactor desired_scale_factor) {
  gfx::Size scaled_size = gfx::ScaleToCeiledSize(
      gfx::Size(source_bitmap.width(), source_bitmap.height()),
      ui::GetScaleForResourceScaleFactor(desired_scale_factor) /
          ui::GetScaleForResourceScaleFactor(source_scale_factor));
  SkBitmap scaled_bitmap;
  scaled_bitmap.allocN32Pixels(scaled_size.width(), scaled_size.height());
  scaled_bitmap.eraseARGB(0, 0, 0, 0);
  SkCanvas canvas(scaled_bitmap, SkSurfaceProps{});
  SkRect scaled_bounds = RectToSkRect(gfx::Rect(scaled_size));
  // Note(oshima): The following scaling code doesn't work with
  // a mask image.
  canvas.drawImageRect(source_bitmap.asImage(), scaled_bounds,
                       SkSamplingOptions());
  return scaled_bitmap;
}

// A ImageSkiaSource that scales 100P image to the target scale factor
// if the ImageSkiaRep for the target scale factor isn't available.
class ThemeImageSource : public gfx::ImageSkiaSource {
 public:
  explicit ThemeImageSource(const gfx::ImageSkia& source) : source_(source) {}

  ThemeImageSource(const ThemeImageSource&) = delete;
  ThemeImageSource& operator=(const ThemeImageSource&) = delete;

  ~ThemeImageSource() override = default;

  gfx::ImageSkiaRep GetImageForScale(float scale) override {
    if (source_.HasRepresentation(scale)) {
      return source_.GetRepresentation(scale);
    }
    const gfx::ImageSkiaRep& rep_100p = source_.GetRepresentation(1.0f);
    SkBitmap scaled_bitmap = CreateLowQualityResizedBitmap(
        rep_100p.GetBitmap(), ui::k100Percent,
        ui::GetSupportedResourceScaleFactor(scale));
    return gfx::ImageSkiaRep(scaled_bitmap, scale);
  }

 private:
  const gfx::ImageSkia source_;
};

// An ImageSkiaSource that delays decoding PNG data into bitmaps until
// needed. Missing data for a scale factor is computed by scaling data for an
// available scale factor. Computed bitmaps are stored for future look up.
class ThemeImagePngSource : public gfx::ImageSkiaSource {
 public:
  typedef std::map<ui::ResourceScaleFactor,
                   scoped_refptr<base::RefCountedMemory>>
      PngMap;

  explicit ThemeImagePngSource(const PngMap& png_map) : png_map_(png_map) {}

  ThemeImagePngSource(const ThemeImagePngSource&) = delete;
  ThemeImagePngSource& operator=(const ThemeImagePngSource&) = delete;

  ~ThemeImagePngSource() override = default;

 private:
  gfx::ImageSkiaRep GetImageForScale(float scale) override {
    ui::ResourceScaleFactor scale_factor =
        ui::GetSupportedResourceScaleFactor(scale);
    // Look up the bitmap for |scale factor| in the bitmap map. If found
    // return it.
    BitmapMap::const_iterator exact_bitmap_it = bitmap_map_.find(scale_factor);
    if (exact_bitmap_it != bitmap_map_.end()) {
      return gfx::ImageSkiaRep(exact_bitmap_it->second, scale);
    }

    // Look up the raw PNG data for |scale_factor| in the png map. If found,
    // decode it, store the result in the bitmap map and return it.
    PngMap::const_iterator exact_png_it = png_map_.find(scale_factor);
    if (exact_png_it != png_map_.end()) {
      SkBitmap bitmap = gfx::PNGCodec::Decode(*exact_png_it->second);
      if (bitmap.isNull()) {
        // The image is either broken or a different format.
        return gfx::ImageSkiaRep();
      }
      bitmap_map_[scale_factor] = bitmap;
      return gfx::ImageSkiaRep(bitmap, scale);
    }

    // Find an available PNG for another scale factor. We want to use the
    // highest available scale factor.
    PngMap::const_iterator available_png_it = png_map_.end();
    for (PngMap::const_iterator png_it = png_map_.begin();
         png_it != png_map_.end(); ++png_it) {
      if (available_png_it == png_map_.end() ||
          ui::GetScaleForResourceScaleFactor(png_it->first) >
              ui::GetScaleForResourceScaleFactor(available_png_it->first)) {
        available_png_it = png_it;
      }
    }
    if (available_png_it == png_map_.end()) {
      return gfx::ImageSkiaRep();
    }
    ui::ResourceScaleFactor available_scale_factor = available_png_it->first;

    // Look up the bitmap for |available_scale_factor| in the bitmap map.
    // If not found, decode the corresponging png data, store the result
    // in the bitmap map.
    BitmapMap::const_iterator available_bitmap_it =
        bitmap_map_.find(available_scale_factor);
    if (available_bitmap_it == bitmap_map_.end()) {
      SkBitmap available_bitmap =
          gfx::PNGCodec::Decode(*available_png_it->second);
      if (available_bitmap.isNull()) {
        NOTREACHED();
      }
      bitmap_map_[available_scale_factor] = available_bitmap;
      available_bitmap_it = bitmap_map_.find(available_scale_factor);
    }

    // Scale the available bitmap to the desired scale factor, store the result
    // in the bitmap map and return it.
    SkBitmap scaled_bitmap = CreateLowQualityResizedBitmap(
        available_bitmap_it->second, available_scale_factor, scale_factor);
    bitmap_map_[scale_factor] = scaled_bitmap;
    return gfx::ImageSkiaRep(scaled_bitmap, scale);
  }

  PngMap png_map_;

  typedef std::map<ui::ResourceScaleFactor, SkBitmap> BitmapMap;
  BitmapMap bitmap_map_;
};

class TabBackgroundImageSource : public gfx::CanvasImageSource {
 public:
  TabBackgroundImageSource(SkColor background_color,
                           const gfx::ImageSkia& image_to_tint,
                           const gfx::ImageSkia& overlay,
                           const color_utils::HSL& hsl_shift,
                           int vertical_offset)
      : gfx::CanvasImageSource(image_to_tint.isNull() ? overlay.size()
                                                      : image_to_tint.size()),
        background_color_(background_color),
        image_to_tint_(image_to_tint),
        overlay_(overlay),
        hsl_shift_(hsl_shift),
        vertical_offset_(vertical_offset) {}

  TabBackgroundImageSource(const TabBackgroundImageSource&) = delete;
  TabBackgroundImageSource& operator=(const TabBackgroundImageSource&) = delete;

  ~TabBackgroundImageSource() override = default;

  // Overridden from CanvasImageSource:
  void Draw(gfx::Canvas* canvas) override {
    canvas->DrawColor(background_color_);

    // Begin with the frame background image, if any.  Since the frame and tabs
    // have grown taller and changed alignment over time, not all themes have a
    // sufficiently tall image; tiling by vertically mirroring in this case is
    // the least-glitchy-looking option.  Note that the behavior here needs to
    // stay in sync with how the browser frame will actually be drawn.
    if (!image_to_tint_.isNull()) {
      gfx::ImageSkia bg_tint = gfx::ImageSkiaOperations::CreateHSLShiftedImage(
          image_to_tint_, hsl_shift_);
      canvas->TileImageInt(bg_tint, 0, vertical_offset_, 0, 0, size().width(),
                           size().height(), 1.0f, SkTileMode::kRepeat,
                           SkTileMode::kMirror);
    }

    // If the theme has a custom tab background image, overlay it.  Vertical
    // mirroring is used for the same reason as above.  This behavior needs to
    // stay in sync with how tabs are drawn.
    if (!overlay_.isNull()) {
      canvas->TileImageInt(overlay_, 0, 0, 0, 0, size().width(),
                           size().height(), 1.0f, SkTileMode::kRepeat,
                           SkTileMode::kMirror);
    }
  }

 private:
  const SkColor background_color_;
  const gfx::ImageSkia image_to_tint_;
  const gfx::ImageSkia overlay_;
  const color_utils::HSL hsl_shift_;
  const int vertical_offset_;
};

class ControlButtonBackgroundImageSource : public gfx::CanvasImageSource {
 public:
  ControlButtonBackgroundImageSource(SkColor background_color,
                                     const gfx::ImageSkia& bg_image,
                                     const gfx::Size& dest_size)
      : gfx::CanvasImageSource(dest_size),
        background_color_(background_color),
        bg_image_(bg_image) {
    DCHECK(!bg_image.isNull());
  }

  ControlButtonBackgroundImageSource(
      const ControlButtonBackgroundImageSource&) = delete;
  ControlButtonBackgroundImageSource& operator=(
      const ControlButtonBackgroundImageSource&) = delete;

  ~ControlButtonBackgroundImageSource() override = default;

  void Draw(gfx::Canvas* canvas) override {
    canvas->DrawColor(background_color_);

    if (!bg_image_.isNull()) {
      canvas->DrawImageInt(bg_image_, 0, 0);
    }
  }

 private:
  const SkColor background_color_;
  const gfx::ImageSkia bg_image_;
};

// Returns whether the color is grayscale.
bool IsColorGrayscale(SkColor color) {
  constexpr int kChannelTolerance = 9;
  auto channels = {SkColorGetR(color), SkColorGetG(color), SkColorGetB(color)};
  const int range = std::max(channels) - std::min(channels);
  return range < kChannelTolerance;
}

// The minimum contrast the omnibox background must have against the toolbar.
constexpr float kMinOmniboxToolbarContrast = 1.3f;

ui::ColorTransform ChooseOmniboxBgBlendTarget() {
  return base::BindRepeating(
      [](SkColor input_color, const ui::ColorMixer& mixer) {
        const SkColor toolbar_color = mixer.GetResultColor(kColorToolbar);
        const SkColor endpoint_color =
            color_utils::GetEndpointColorWithMinContrast(toolbar_color);
        return (color_utils::GetContrastRatio(toolbar_color, endpoint_color) >=
                kMinOmniboxToolbarContrast)
                   ? endpoint_color
                   : color_utils::GetColorWithMaxContrast(endpoint_color);
      });
}

}  // namespace

BrowserThemePack::~BrowserThemePack() {
  DCHECK(!data_pack_ || using_data_pack_);

  if (using_data_pack_) {
    if (data_pack_) {
      auto task_runner = base::ThreadPool::CreateSequencedTaskRunner(
          {base::MayBlock(), base::TaskPriority::BEST_EFFORT});
      DCHECK(task_runner);
      task_runner->DeleteSoon(FROM_HERE, std::move(data_pack_));
    }
  } else {
    // When not using a data_pack, the memory is allocated and must be freed.
    delete header_;
    delete[] tints_;
    delete[] colors_;
    delete[] display_properties_;
    delete[] source_images_;
  }
}

void BrowserThemePack::SetColor(int id, SkColor color) {
  DCHECK(colors_);

  int first_available_color = -1;
  for (size_t i = 0; i < kColorsArrayLength; ++i) {
    if (colors_[i].id == id) {
      colors_[i].color = color;
      return;
    }
    if (colors_[i].id == -1 && first_available_color == -1) {
      first_available_color = i;
    }
  }

  DCHECK_NE(-1, first_available_color);
  colors_[first_available_color].id = id;
  colors_[first_available_color].color = color;
}

void BrowserThemePack::SetColorIfUnspecified(int id, SkColor color) {
  SkColor temp_color;
  if (!GetColor(id, &temp_color)) {
    SetColor(id, color);
  }
}

void BrowserThemePack::SetTint(int id, color_utils::HSL tint) {
  DCHECK(tints_);

  int first_available_index = -1;
  for (size_t i = 0; i < kTintTableLength; ++i) {
    if (tints_[i].id == id) {
      tints_[i].h = tint.h;
      tints_[i].s = tint.s;
      tints_[i].l = tint.l;
      return;
    }
    if (tints_[i].id == -1 && first_available_index == -1) {
      first_available_index = i;
    }
  }

  DCHECK_NE(-1, first_available_index);
  tints_[first_available_index].id = id;
  tints_[first_available_index].h = tint.h;
  tints_[first_available_index].s = tint.s;
  tints_[first_available_index].l = tint.l;
}

void BrowserThemePack::SetDisplayProperty(int id, int value) {
  DCHECK(display_properties_);

  int first_available_index = -1;
  for (size_t i = 0; i < kDisplayPropertiesSize; ++i) {
    if (display_properties_[i].id == id) {
      display_properties_[i].property = value;
      return;
    }
    if (display_properties_[i].id == -1 && first_available_index == -1) {
      first_available_index = i;
    }
  }

  DCHECK_NE(-1, first_available_index);
  display_properties_[first_available_index].id = id;
  display_properties_[first_available_index].property = value;
}

SkColor BrowserThemePack::ComputeImageColor(const gfx::Image& image,
                                            int height) {
  // Include all colors in the analysis.
  constexpr color_utils::HSL kNoBounds = {-1, -1, -1};
  const SkColor color = color_utils::CalculateKMeanColorOfBitmap(
      *image.ToSkBitmap(), height, kNoBounds, kNoBounds, false);

  return color;
}

// static
void BrowserThemePack::BuildFromExtension(
    const extensions::Extension* extension,
    BrowserThemePack* pack) {
  DCHECK(extension);
  DCHECK(extension->is_theme());
  DCHECK(!pack->is_valid());

  // NOTE! If you make any changes here, please update kThemePackVersion.

  pack->InitEmptyPack();
  pack->set_extension_id(extension->id());
  pack->SetHeaderId(extension);
  pack->SetTintsFromJSON(extensions::ThemeInfo::GetTints(extension));
  pack->SetColorsFromJSON(extensions::ThemeInfo::GetColors(extension));
  pack->SetDisplayPropertiesFromJSON(
      extensions::ThemeInfo::GetDisplayProperties(extension));

  // Builds the images. (Image building is dependent on tints).
  FilePathMap file_paths;
  pack->ParseImageNamesFromJSON(extensions::ThemeInfo::GetImages(extension),
                                extension->path(), &file_paths);
  pack->BuildSourceImagesArray(file_paths);

  if (!pack->LoadRawBitmapsTo(file_paths, &pack->images_)) {
    return;
  }

  pack->AdjustThemePack();

  // The BrowserThemePack is now in a consistent state.
  pack->is_valid_ = true;
}

// static
scoped_refptr<BrowserThemePack> BrowserThemePack::BuildFromDataPack(
    const base::FilePath& path,
    const std::string& expected_id) {
  DCHECK_CURRENTLY_ON(BrowserThread::UI);
  // Allow IO on UI thread due to deep-seated theme design issues.
  // (see http://crbug.com/80206)
  base::ScopedAllowBlocking scoped_allow_blocking;

  // For now data pack can only have extension type.
  scoped_refptr<BrowserThemePack> pack(
      new BrowserThemePack(ThemeType::kExtension));
  pack->set_extension_id(expected_id);

  // The data pack is loaded in a local variable to be released synchronously
  // in case of failures (see https://crbug.com/1292632).
  // Scale factor parameter is moot as data pack has image resources for all
  // supported scale factors.
  std::unique_ptr<ui::DataPack> data_pack =
      std::make_unique<ui::DataPack>(ui::kScaleFactorNone);

  // The browser theme pack is using a data pack.
  pack->using_data_pack_ = true;

  if (!data_pack->LoadFromPath(path)) {
    LOG(ERROR) << "Failed to load theme data pack.";
    return nullptr;
  }

  std::optional<std::string_view> pointer = data_pack->GetStringView(kHeaderID);
  if (!pointer) {
    return nullptr;
  }
  pack->header_ = reinterpret_cast<BrowserThemePackHeader*>(
      const_cast<char*>(pointer->data()));

  if (pack->header_->version != kThemePackVersion) {
    DLOG(ERROR) << "BuildFromDataPack failure! Version mismatch!";
    return nullptr;
  }
  // TODO(erg): Check endianess once DataPack works on the other endian.
  std::string theme_id(reinterpret_cast<char*>(pack->header_->theme_id),
                       crx_file::id_util::kIdSize);
  std::string truncated_id = expected_id.substr(0, crx_file::id_util::kIdSize);
  if (theme_id != truncated_id) {
    DLOG(ERROR) << "Wrong id: " << theme_id << " vs " << expected_id;
    return nullptr;
  }

  pointer = data_pack->GetStringView(kTintsID);
  if (!pointer) {
    return nullptr;
  }
  pack->tints_ =
      reinterpret_cast<TintEntry*>(const_cast<char*>(pointer->data()));

  pointer = data_pack->GetStringView(kColorsID);
  if (!pointer) {
    return nullptr;
  }
  pack->colors_ =
      reinterpret_cast<ColorPair*>(const_cast<char*>(pointer->data()));

  pointer = data_pack->GetStringView(kDisplayPropertiesID);
  if (!pointer) {
    return nullptr;
  }
  pack->display_properties_ = reinterpret_cast<DisplayPropertyPair*>(
      const_cast<char*>(pointer->data()));

  pointer = data_pack->GetStringView(kSourceImagesID);
  if (!pointer) {
    return nullptr;
  }
  pack->source_images_ =
      reinterpret_cast<SourceImage*>(const_cast<char*>(pointer->data()));

  pointer = data_pack->GetStringView(kScaleFactorsID);
  if (!pointer) {
    return nullptr;
  }

  if (!InputScalesValid(pointer.value(), pack->scale_factors_)) {
    DLOG(ERROR) << "BuildFromDataPack failure! The pack scale factors differ "
                << "from those supported by platform.";
    return nullptr;
  }

  // The loaded pack is valid and can be used as a theme pack.
  pack->data_pack_ = std::move(data_pack);
  pack->is_valid_ = true;

  return pack;
}

// static
bool BrowserThemePack::IsPersistentImageID(int id) {
  return GetPersistentIDByIDR(id) != PersistentID::kInvalid;
}

// static
void BrowserThemePack::BuildFromColor(SkColor color, BrowserThemePack* pack) {
  BuildFromColors(GetAutogeneratedThemeColors(color), pack);
}

// static
void BrowserThemePack::BuildFromColors(AutogeneratedThemeColors colors,
                                       BrowserThemePack* pack) {
  pack->InitEmptyPackFromColors();

  // NOTE! If you make any changes here, please update kThemePackVersion.

  // Frame.
  pack->SetColor(TP::COLOR_FRAME_ACTIVE, colors.frame_color);

  // Inactive tab uses frame color.
  pack->SetColor(TP::COLOR_TAB_BACKGROUND_INACTIVE_FRAME_ACTIVE,
                 colors.frame_color);
  pack->SetColor(TP::COLOR_TAB_FOREGROUND_INACTIVE_FRAME_ACTIVE,
                 colors.frame_text_color);

  // Toolbar and active tab (set in SetFrameAndToolbarRelatedColors) use active
  // tab color.
  pack->SetColor(TP::COLOR_TOOLBAR, colors.active_tab_color);
  pack->SetColor(TP::COLOR_TOOLBAR_TEXT, colors.active_tab_text_color);
  pack->SetColor(TP::COLOR_TOOLBAR_BUTTON_ICON, colors.active_tab_text_color);

  // NTP.
  pack->SetColor(TP::COLOR_NTP_BACKGROUND, colors.ntp_color);
  pack->SetColor(TP::COLOR_NTP_TEXT,
                 color_utils::GetColorWithMaxContrast(colors.ntp_color));

  // Always use alternate logo (not colorful one) for all backgrounds except
  // white.
  if (colors.active_tab_color != SK_ColorWHITE) {
    pack->SetDisplayProperty(TP::NTP_LOGO_ALTERNATE, 1);
  }

  // Don't change frame color for inactive window.
  pack->SetTint(TP::TINT_FRAME_INACTIVE, {-1, -1, -1});
  pack->SetTint(TP::TINT_FRAME_INCOGNITO_INACTIVE, {-1, -1, -1});

  pack->FinalizePackFromColors();
}

void BrowserThemePack::BuildFromWebAppColors(SkColor theme_color,
                                             SkColor background_color,
                                             BrowserThemePack* pack) {
  pack->InitEmptyPackFromColors();

  // NOTE! If you make any changes here, please update kThemePackVersion.

  // Frame and inactive tab use the theme color.
  pack->SetColor(TP::COLOR_FRAME_ACTIVE, theme_color);
  pack->SetColor(TP::COLOR_TAB_BACKGROUND_INACTIVE_FRAME_ACTIVE, theme_color);
  SkColor theme_text_color = color_utils::GetColorWithMaxContrast(theme_color);
  pack->SetColor(TP::COLOR_TAB_FOREGROUND_INACTIVE_FRAME_ACTIVE,
                 theme_text_color);

  // Toolbar also uses theme color.
  pack->SetColor(TP::COLOR_TOOLBAR, theme_color);
  pack->SetColor(TP::COLOR_TOOLBAR_TEXT, theme_text_color);
  pack->SetColor(TP::COLOR_TOOLBAR_BUTTON_ICON, theme_text_color);

  // Active tab however uses background color.
  pack->SetColor(TP::COLOR_TAB_BACKGROUND_ACTIVE_FRAME_ACTIVE,
                 background_color);
  pack->SetColor(TP::COLOR_TAB_FOREGROUND_ACTIVE_FRAME_ACTIVE,
                 color_utils::GetColorWithMaxContrast(background_color));

  // Don't change frame color for inactive window.
  pack->SetTint(TP::TINT_FRAME_INACTIVE, {-1, -1, -1});
  pack->SetTint(TP::TINT_FRAME_INCOGNITO_INACTIVE, {-1, -1, -1});

  pack->FinalizePackFromColors();
}

BrowserThemePack::BrowserThemePack(ThemeType theme_type)
    : CustomThemeSupplier(theme_type) {
  scale_factors_ = ui::GetSupportedResourceScaleFactors();
}

bool BrowserThemePack::WriteToDisk(const base::FilePath& path) const {
  // Add resources for each of the property arrays.
  RawDataForWriting resources;
  resources[kHeaderID] =
      std::string_view(reinterpret_cast<const char*>(header_.get()),
                       sizeof(BrowserThemePackHeader));
  resources[kTintsID] =
      std::string_view(reinterpret_cast<const char*>(tints_.get()),
                       sizeof(TintEntry[kTintTableLength]));
  resources[kColorsID] =
      std::string_view(reinterpret_cast<const char*>(colors_.get()),
                       sizeof(ColorPair[kColorsArrayLength]));
  resources[kDisplayPropertiesID] =
      std::string_view(reinterpret_cast<const char*>(display_properties_.get()),
                       sizeof(DisplayPropertyPair[kDisplayPropertiesSize]));

  int source_count = 1;
  SourceImage* end = source_images_;
  for (; end->id != -1; end++) {
    source_count++;
  }
  resources[kSourceImagesID] =
      std::string_view(reinterpret_cast<const char*>(source_images_.get()),
                       source_count * sizeof(*source_images_));

  // Store results of GetResourceScaleFactorsAsString() in std::string as
  // std::string_view does not copy data in constructor.
  std::string scale_factors_string =
      GetResourceScaleFactorsAsString(scale_factors_);
  resources[kScaleFactorsID] = scale_factors_string;

  AddRawImagesTo(image_memory_, &resources);

  RawImages reencoded_images;
  RepackImages(images_on_file_thread_, &reencoded_images);
  AddRawImagesTo(reencoded_images, &resources);

  return ui::DataPack::WritePack(path, resources, ui::DataPack::BINARY);
}

bool BrowserThemePack::GetTint(int id, color_utils::HSL* hsl) const {
  if (tints_) {
    for (size_t i = 0; i < kTintTableLength; ++i) {
      if (tints_[i].id == id) {
        hsl->h = tints_[i].h;
        hsl->s = tints_[i].s;
        hsl->l = tints_[i].l;
        return true;
      }
    }
  }

  return false;
}

bool BrowserThemePack::GetColor(int id, SkColor* color) const {
  static constexpr auto kOpaqueColors =
      base::MakeFixedFlatSet<TP::OverwritableByUserThemeProperty>({
          // Background tabs must be opaque since the tabstrip expects to be
          // able to render text opaquely atop them.
          TP::COLOR_TAB_BACKGROUND_INACTIVE_FRAME_ACTIVE,
          TP::COLOR_TAB_BACKGROUND_INACTIVE_FRAME_INACTIVE,
          TP::COLOR_TAB_BACKGROUND_INACTIVE_FRAME_ACTIVE_INCOGNITO,
          TP::COLOR_TAB_BACKGROUND_INACTIVE_FRAME_INACTIVE_INCOGNITO,
          // The frame colors will be used for background tabs when not
          // otherwise overridden and thus must be opaque as well.
          TP::COLOR_FRAME_ACTIVE,
          TP::COLOR_FRAME_INACTIVE,
          TP::COLOR_FRAME_ACTIVE_INCOGNITO,
          TP::COLOR_FRAME_INACTIVE_INCOGNITO,
          // The toolbar is used as the foreground tab color, so it must be
          // opaque just like background tabs.
          TP::COLOR_TOOLBAR,
      });

  if (colors_) {
    for (size_t i = 0; i < kColorsArrayLength; ++i) {
      if (colors_[i].id == id) {
        *color = colors_[i].color;
        if (base::Contains(kOpaqueColors, id)) {
          *color = SkColorSetA(*color, SK_AlphaOPAQUE);
        }
        return true;
      }
    }
  }

  return false;
}

bool BrowserThemePack::GetDisplayProperty(int id, int* result) const {
  if (display_properties_) {
    for (size_t i = 0; i < kDisplayPropertiesSize; ++i) {
      if (display_properties_[i].id == id) {
        *result = display_properties_[i].property;
        return true;
      }
    }
  }

  return false;
}

gfx::Image BrowserThemePack::GetImageNamed(int idr_id) const {
  PersistentID prs_id = GetPersistentIDByIDR(idr_id);
  if (prs_id == PersistentID::kInvalid) {
    return gfx::Image();
  }

  // Check if the image is cached.
  ImageCache::const_iterator image_iter = images_.find(prs_id);
  if (image_iter != images_.end()) {
    return image_iter->second;
  }

  ThemeImagePngSource::PngMap png_map;
  for (auto scale_factor : scale_factors_) {
    scoped_refptr<base::RefCountedMemory> memory =
        GetRawData(idr_id, scale_factor);
    if (memory.get()) {
      png_map[scale_factor] = memory;
    }
  }
  if (!png_map.empty()) {
    gfx::ImageSkia image_skia(std::make_unique<ThemeImagePngSource>(png_map),
                              1.0f);
    gfx::Image ret = gfx::Image(image_skia);
    images_[prs_id] = ret;
    return ret;
  }

  return gfx::Image();
}

base::RefCountedMemory* BrowserThemePack::GetRawData(
    int idr_id,
    ui::ResourceScaleFactor scale_factor) const {
  base::RefCountedMemory* memory = nullptr;
  PersistentID prs_id = GetPersistentIDByIDR(idr_id);
  int raw_id = GetRawIDByPersistentID(prs_id, scale_factor);

  if (raw_id != -1) {
    if (data_pack_.get()) {
      memory = data_pack_->GetStaticMemory(raw_id);
    } else {
      auto it = image_memory_.find(raw_id);
      if (it != image_memory_.end()) {
        memory = it->second.get();
      }
    }
  }

  return memory;
}

bool BrowserThemePack::HasCustomImage(int idr_id) const {
  PersistentID prs_id = GetPersistentIDByIDR(idr_id);
  if (prs_id == PersistentID::kInvalid) {
    return false;
  }

  SourceImage* img = source_images_;
  for (; img->id != -1; ++img) {
    if (img->id == prs_id) {
      return true;
    }
  }

  return false;
}

void BrowserThemePack::AddColorMixers(ui::ColorProvider* provider,
                                      const ui::ColorProviderKey& key) const {
  ui::ColorMixer& mixer = provider->AddMixer();

  // TODO(http://crbug.com/878664): Enable for all cases.
  mixer[kColorToolbarBackgroundSubtleEmphasis] = ui::BlendForMinContrast(
      kColorToolbar, kColorToolbar, ChooseOmniboxBgBlendTarget(),
      kMinOmniboxToolbarContrast);

  // A map from theme property IDs to color IDs for use in color mixers.
  constexpr struct {
    int property_id;
    int color_id;
  } kThemePropertiesMap[] = {
      {TP::COLOR_BOOKMARK_TEXT, kColorBookmarkBarForeground},
      {TP::COLOR_CONTROL_BUTTON_BACKGROUND, kColorCaptionButtonBackground},
      {TP::COLOR_FRAME_ACTIVE, ui::kColorFrameActive},
      {TP::COLOR_FRAME_INACTIVE, ui::kColorFrameInactive},
      {TP::COLOR_NTP_BACKGROUND, kColorNewTabPageBackground},
      {TP::COLOR_NTP_HEADER, kColorNewTabPageHeader},
      {TP::COLOR_NTP_LINK, kColorNewTabPageLink},
      {TP::COLOR_NTP_LOGO, kColorNewTabPageLogo},
      {TP::COLOR_NTP_SECTION_BORDER, kColorNewTabPageSectionBorder},
      {TP::COLOR_NTP_TEXT, kColorNewTabPageText},
      {TP::COLOR_OMNIBOX_TEXT, kColorOmniboxText},
      {TP::COLOR_OMNIBOX_BACKGROUND, kColorToolbarBackgroundSubtleEmphasis},
      {TP::COLOR_TAB_BACKGROUND_INACTIVE_FRAME_ACTIVE,
       kColorTabBackgroundInactiveFrameActive},
      {TP::COLOR_TAB_BACKGROUND_INACTIVE_FRAME_INACTIVE,
       kColorTabBackgroundInactiveFrameInactive},
      {TP::COLOR_TAB_FOREGROUND_ACTIVE_FRAME_ACTIVE,
       kColorTabForegroundActiveFrameActive},
      {TP::COLOR_TAB_FOREGROUND_ACTIVE_FRAME_INACTIVE,
       kColorTabForegroundActiveFrameInactive},
      {TP::COLOR_TAB_FOREGROUND_INACTIVE_FRAME_ACTIVE,
       kColorTabForegroundInactiveFrameActive},
      {TP::COLOR_TAB_FOREGROUND_INACTIVE_FRAME_INACTIVE,
       kColorTabForegroundInactiveFrameInactive},
      {TP::COLOR_TAB_THROBBER_SPINNING, kColorTabThrobber},
      {TP::COLOR_TAB_THROBBER_WAITING, kColorTabThrobberPreconnect},
      {TP::COLOR_TOOLBAR, kColorToolbar},
      {TP::COLOR_TOOLBAR_BUTTON_ICON, kColorToolbarButtonIcon},
      {TP::COLOR_TOOLBAR_BUTTON_ICON_HOVERED, kColorToolbarButtonIconHovered},
      {TP::COLOR_TOOLBAR_BUTTON_ICON_PRESSED, kColorToolbarButtonIconPressed},
      {TP::COLOR_TOOLBAR_TEXT, kColorToolbarText},
      {TP::COLOR_WINDOW_CONTROL_BUTTON_BACKGROUND_ACTIVE,
       kColorWindowControlButtonBackgroundActive},
      {TP::COLOR_WINDOW_CONTROL_BUTTON_BACKGROUND_INACTIVE,
       kColorWindowControlButtonBackgroundInactive}};

  SkColor color;
  for (const auto& entry : kThemePropertiesMap) {
    if (GetColor(entry.property_id, &color)) {
      mixer[entry.color_id] = {color};
    }
  }

  if (GetColor(TP::COLOR_TOOLBAR_BUTTON_ICON, &color)) {
    mixer[kColorBookmarkFavicon] = {kColorToolbarButtonIcon};
  }

  if (GetColor(TP::COLOR_BOOKMARK_TEXT, &color)) {
    mixer[kColorBookmarkFolderIcon] =
        ui::DeriveDefaultIconColor(kColorBookmarkBarForeground);
  }

  int result = 0;
  if (GetDisplayProperty(TP::SHOULD_FILL_BACKGROUND_TAB_COLOR, &result) &&
      result == 0) {
    mixer[kColorNewTabButtonBackgroundFrameActive] = {SK_ColorTRANSPARENT};
    mixer[kColorNewTabButtonBackgroundFrameInactive] = {SK_ColorTRANSPARENT};
  }
}

// private:

void BrowserThemePack::AdjustThemePack() {
  CropImages(&images_);

  // Create toolbar image, and generate toolbar color from image where relevant.
  // This must be done after reading colors from JSON (so they can be used for
  // compositing the image).
  CreateToolbarImageAndColors(&images_);

  // Create frame images, and generate frame colors from images where relevant.
  // This must be done after reading colors from JSON (so they can be used for
  // compositing the image).
  CreateFrameImagesAndColors(&images_);

  // Generate any missing frame colors from tints. This must be done after
  // generating colors from the frame images, so only colors with no matching
  // images are generated.
  GenerateFrameColorsFromTints();

  // Set frame and toolbar related elements' colors (e.g. status bubble,
  // info bar, download shelf) to frame or toolbar color.
  SetFrameAndToolbarRelatedColors();

  // Generate background color information for window control buttons.  This
  // must be done after frame colors are set, since they are used when
  // determining window control button colors.
  GenerateWindowControlButtonColor(&images_);

  // Create the tab background images, and generate colors where relevant.  This
  // must be done after all frame colors are set, since they are used when
  // creating these.
  CreateTabBackgroundImagesAndColors(&images_);

  // Make sure the |images_on_file_thread_| has bitmaps for supported
  // scale factors before passing to FILE thread.
  images_on_file_thread_ = images_;
  for (auto& image : images_on_file_thread_) {
    gfx::ImageSkia* image_skia =
        const_cast<gfx::ImageSkia*>(image.second.ToImageSkia());
    image_skia->MakeThreadSafe();
  }

  // Set ThemeImageSource on |images_| to resample the source
  // image if a caller of BrowserThemePack::GetImageNamed() requests an
  // ImageSkiaRep for a scale factor not specified by the theme author.
  // Callers of BrowserThemePack::GetImageNamed() to be able to retrieve
  // ImageSkiaReps for all supported scale factors.
  for (auto& image : images_) {
    const gfx::ImageSkia source_image_skia = image.second.AsImageSkia();
    auto source = std::make_unique<ThemeImageSource>(source_image_skia);
    gfx::ImageSkia image_skia(std::move(source), source_image_skia.size());
    image.second = gfx::Image(image_skia);
  }

  // Generate raw images (for new-tab-page attribution and background) for
  // any missing scale from an available scale image.
  for (auto kPreloadID : kPreloadIDs) {
    GenerateRawImageForAllSupportedScales(kPreloadID);
  }

  // Generates missing NTP related colors. Should be called after theme images
  // are prepared.
  GenerateMissingNtpColors();
}

void BrowserThemePack::InitEmptyPack() {
  InitHeader();

  InitTints();

  InitColors();

  InitDisplayProperties();
}

void BrowserThemePack::InitEmptyPackFromColors() {
  DCHECK(!is_valid());
  InitEmptyPack();

  // Init `source_images_` only here as other code paths initialize it
  // differently.
  InitSourceImages();
}

void BrowserThemePack::InitHeader() {
  header_ = new BrowserThemePackHeader;
  header_->version = kThemePackVersion;

// TODO(erg): Need to make this endian safe on other computers. Prerequisite
// is that ui::DataPack removes this same check.
#if defined(__BYTE_ORDER)
  // Linux check
  static_assert(__BYTE_ORDER == __LITTLE_ENDIAN,
                "datapack assumes little endian");
#elif defined(__BIG_ENDIAN__)
  // Mac check
#error DataPack assumes little endian
#endif
  header_->little_endian = 1;
}

void BrowserThemePack::InitTints() {
  tints_ = new TintEntry[kTintTableLength];
  for (size_t i = 0; i < kTintTableLength; ++i) {
    tints_[i].id = -1;
    tints_[i].h = -1;
    tints_[i].s = -1;
    tints_[i].l = -1;
  }
}

void BrowserThemePack::InitColors() {
  colors_ = new ColorPair[kColorsArrayLength];
  for (size_t i = 0; i < kColorsArrayLength; ++i) {
    colors_[i].id = -1;
    colors_[i].color = SkColorSetRGB(0, 0, 0);
  }
}

void BrowserThemePack::InitDisplayProperties() {
  display_properties_ = new DisplayPropertyPair[kDisplayPropertiesSize];
  for (size_t i = 0; i < kDisplayPropertiesSize; ++i) {
    display_properties_[i].id = -1;
    display_properties_[i].property = 0;
  }
}

void BrowserThemePack::InitSourceImages() {
  source_images_ = new SourceImage[1];
  source_images_[0].id = -1;
}

void BrowserThemePack::FinalizePackFromColors() {
  AdjustThemePack();

  // The BrowserThemePack is now in a consistent state.
  is_valid_ = true;
}

void BrowserThemePack::SetHeaderId(const Extension* extension) {
  DCHECK(header_);
  const std::string& id = extension->id();
  memcpy(header_->theme_id, id.c_str(), crx_file::id_util::kIdSize);
}

void BrowserThemePack::SetTintsFromJSON(const base::Value::Dict* tints_value) {
  DCHECK(tints_);

  if (!tints_value) {
    return;
  }

  // Parse the incoming data from |tints_value| into an intermediary structure.
  std::map<int, color_utils::HSL> temp_tints;
  for (const auto [key, value] : *tints_value) {
    if (!value.is_list()) {
      continue;
    }

    const base::Value::List& tint_list = value.GetList();
    if (tint_list.size() != 3) {
      continue;
    }

    std::optional<double> h = tint_list[0].GetIfDouble();
    std::optional<double> s = tint_list[1].GetIfDouble();
    std::optional<double> l = tint_list[2].GetIfDouble();
    if (!h || !s || !l) {
      continue;
    }

    color_utils::HSL hsl = {*h, *s, *l};
    MakeHSLShiftValid(&hsl);

    int id = GetIntForString(key, kTintTable, kTintTableLength);
    if (id != -1) {
      temp_tints[id] = hsl;
    }
  }

  // Copy data from the intermediary data structure to the array.
  size_t count = 0;
  for (std::map<int, color_utils::HSL>::const_iterator it = temp_tints.begin();
       it != temp_tints.end() && count < kTintTableLength; ++it, ++count) {
    tints_[count].id = it->first;
    tints_[count].h = it->second.h;
    tints_[count].s = it->second.s;
    tints_[count].l = it->second.l;
  }
}

void BrowserThemePack::SetColorsFromJSON(
    const base::Value::Dict* colors_value) {
  DCHECK(colors_);

  std::map<int, SkColor> temp_colors;
  if (colors_value) {
    ReadColorsFromJSON(*colors_value, &temp_colors);
  }

  // Copy data from the intermediary data structure to the array.
  size_t count = 0;
  for (std::map<int, SkColor>::const_iterator it = temp_colors.begin();
       it != temp_colors.end() && count < kOverwritableColorTableLength;
       ++it, ++count) {
    colors_[count].id = it->first;
    colors_[count].color = it->second;
  }
}

void BrowserThemePack::ReadColorsFromJSON(const base::Value::Dict& colors_value,
                                          std::map<int, SkColor>* temp_colors) {
  // Parse the incoming data from |colors_value| into an intermediary structure.
  for (const auto [key, value] : colors_value) {
    if (!value.is_list()) {
      continue;
    }
    const base::Value::List& color_list = value.GetList();
    if (!(color_list.size() == 3 || color_list.size() == 4)) {
      continue;
    }

    SkColor color = SK_ColorWHITE;
    std::optional<int> r = color_list[0].GetIfInt();
    std::optional<int> g = color_list[1].GetIfInt();
    std::optional<int> b = color_list[2].GetIfInt();
    if (!(r.has_value() && r.value() >= 0 && r.value() <= 255 &&
          g.has_value() && g.value() >= 0 && g.value() <= 255 &&
          b.has_value() && b.value() >= 0 && b.value() <= 255)) {
      continue;
    }

    if (color_list.size() == 4) {
      bool alpha_valid = false;
      if (color_list[3].is_int()) {
        int alpha_int = color_list[3].GetInt();
        if (alpha_int == 0 || alpha_int == 1) {
          color = SkColorSetARGB(alpha_int ? 255 : 0, *r, *g, *b);
          alpha_valid = true;
        }
      } else if (color_list[3].is_double()) {
        double alpha = color_list[3].GetDouble();
        if (alpha >= 0 && alpha <= 1) {
          color =
              SkColorSetARGB(base::ClampRound<U8CPU>(alpha * 255), *r, *g, *b);
          alpha_valid = true;
        }
      }

      if (!alpha_valid) {
        continue;
      }
    } else {
      color = SkColorSetRGB(*r, *g, *b);
    }

    if (key == "ntp_section") {
      // We no longer use ntp_section, but to support legacy
      // themes we still need to use it as a fallback for
      // ntp_header.
      if (!temp_colors->count(TP::COLOR_NTP_HEADER)) {
        (*temp_colors)[TP::COLOR_NTP_HEADER] = color;
      }
    } else {
      int id = GetIntForString(key, kOverwritableColorTable,
                               kOverwritableColorTableLength);
      if (id != -1) {
        (*temp_colors)[id] = color;
      }
    }
  }
}

void BrowserThemePack::SetDisplayPropertiesFromJSON(
    const base::Value::Dict* display_properties_value) {
  DCHECK(display_properties_);

  if (!display_properties_value) {
    return;
  }

  std::map<int, int> temp_properties;
  for (const auto [key, value] : *display_properties_value) {
    int property_id =
        GetIntForString(key, kDisplayProperties, kDisplayPropertiesSize);
    switch (property_id) {
      case TP::NTP_BACKGROUND_ALIGNMENT: {
        if (value.is_string()) {
          temp_properties[TP::NTP_BACKGROUND_ALIGNMENT] =
              TP::StringToAlignment(value.GetString());
        }
        break;
      }
      case TP::NTP_BACKGROUND_TILING: {
        if (value.is_string()) {
          temp_properties[TP::NTP_BACKGROUND_TILING] =
              TP::StringToTiling(value.GetString());
        }
        break;
      }
      case TP::NTP_LOGO_ALTERNATE: {
        if (value.is_int()) {
          temp_properties[TP::NTP_LOGO_ALTERNATE] = value.GetInt();
        }
        break;
      }
    }
  }

  // Copy data from the intermediary data structure to the array.
  size_t count = 0;
  for (std::map<int, int>::const_iterator it = temp_properties.begin();
       it != temp_properties.end() && count < kDisplayPropertiesSize;
       ++it, ++count) {
    display_properties_[count].id = it->first;
    display_properties_[count].property = it->second;
  }
}

void BrowserThemePack::ParseImageNamesFromJSON(
    const base::Value::Dict* images_value,
    const base::FilePath& images_path,
    FilePathMap* file_paths) const {
  if (!images_value) {
    return;
  }

  for (const auto [key, value] : *images_value) {
    if (value.is_dict()) {
      for (const auto [inner_key, inner_value] : value.GetDict()) {
        ui::ResourceScaleFactor scale_factor = ui::kScaleFactorNone;
        if (GetScaleFactorFromManifestKey(inner_key, &scale_factor) &&
            inner_value.is_string()) {
          AddFileAtScaleToMap(key, scale_factor,
                              images_path.AppendASCII(inner_value.GetString()),
                              file_paths);
        }
      }
    } else if (value.is_string()) {
      AddFileAtScaleToMap(key, ui::k100Percent,
                          images_path.AppendASCII(value.GetString()),
                          file_paths);
    }
  }
}

void BrowserThemePack::AddFileAtScaleToMap(const std::string& image_name,
                                           ui::ResourceScaleFactor scale_factor,
                                           const base::FilePath& image_path,
                                           FilePathMap* file_paths) const {
  PersistentID id = GetPersistentIDByName(image_name);
  if (id != PersistentID::kInvalid) {
    (*file_paths)[id][scale_factor] = image_path;
  }
}

void BrowserThemePack::BuildSourceImagesArray(const FilePathMap& file_paths) {
  source_images_ = new SourceImage[file_paths.size() + 1];
  std::ranges::transform(
      file_paths, source_images_.get(),
      [](const auto& pair) { return SourceImage{pair.first}; });
  source_images_[file_paths.size()].id = -1;
}

bool BrowserThemePack::LoadRawBitmapsTo(const FilePathMap& file_paths,
                                        ImageCache* image_cache) {
  // Themes should be loaded on the file thread, not the UI thread.
  // http://crbug.com/61838
  base::ScopedAllowBlocking scoped_allow_blocking;

  for (const auto& entry : file_paths) {
    PersistentID prs_id = entry.first;
    // Some images need to go directly into |image_memory_|. No modification is
    // necessary or desirable.
    const bool is_copyable = base::Contains(kPreloadIDs, prs_id);
    gfx::ImageSkia image_skia;
    for (int pass = 0; pass < 2; ++pass) {
      // Two passes: In the first pass, we process only scale factor
      // 100% and in the second pass all other scale factors. We
      // process scale factor 100% first because the first image added
      // in image_skia.AddRepresentation() determines the DIP size for
      // all representations.
      for (const auto& s2f : entry.second) {
        ui::ResourceScaleFactor scale_factor = s2f.first;
        if ((pass == 0 && scale_factor != ui::k100Percent) ||
            (pass == 1 && scale_factor == ui::k100Percent)) {
          continue;
        }
        scoped_refptr<base::RefCountedMemory> raw_data(
            ReadFileData(s2f.second));
        if (!raw_data.get() || !raw_data->size()) {
          LOG(ERROR) << "Could not load theme image" << " prs_id=" << prs_id
                     << " scale_factor_enum=" << scale_factor
                     << " file=" << s2f.second.value()
                     << (raw_data.get() ? " (zero size)" : " (read error)");
          return false;
        }
        if (is_copyable) {
          int raw_id = GetRawIDByPersistentID(prs_id, scale_factor);
          image_memory_[raw_id] = raw_data;
        } else {
          SkBitmap bitmap = gfx::PNGCodec::Decode(*raw_data);
          if (!bitmap.isNull()) {
            image_skia.AddRepresentation(gfx::ImageSkiaRep(
                bitmap, ui::GetScaleForResourceScaleFactor(scale_factor)));
          } else {
            // The image is either broken or a different format.
            return false;
          }
        }
      }
    }
    if (!is_copyable && !image_skia.isNull()) {
      (*image_cache)[prs_id] = gfx::Image(image_skia);
    }
  }

  return true;
}

void BrowserThemePack::CropImages(ImageCache* images) const {
  for (const auto& image_to_crop : kImagesToCrop) {
    auto it = images->find(image_to_crop.prs_id);
    if (it == images->end()) {
      continue;
    }

    gfx::ImageSkia image_skia = it->second.AsImageSkia();
    (*images)[image_to_crop.prs_id] =
        gfx::Image(gfx::ImageSkiaOperations::ExtractSubset(
            image_skia,
            gfx::Rect(0, 0, image_skia.width(), image_to_crop.max_height)));
  }
}

void BrowserThemePack::SetFrameAndToolbarRelatedColors() {
  // Propagate the user-specified toolbar color to similar elements.
  SkColor toolbar_color;
  if (GetColor(TP::COLOR_TOOLBAR, &toolbar_color)) {
    // If the toolbar color is set but the text color is not, ensure it has
    // sufficient contrast.
    SkColor toolbar_text_color =
        TP::GetDefaultColor(TP::COLOR_TOOLBAR_TEXT, false);
    toolbar_text_color =
        color_utils::BlendForMinContrast(toolbar_text_color, toolbar_color)
            .color;
    SetColorIfUnspecified(TP::COLOR_TOOLBAR_TEXT, toolbar_text_color);
  } else {
    toolbar_color = TP::GetDefaultColor(TP::COLOR_TOOLBAR, false);
  }
  SkColor toolbar_button_icon_color;
  color_utils::HSL button_tint;
  if (GetColor(TP::COLOR_TOOLBAR_BUTTON_ICON, &toolbar_button_icon_color)) {
    SetColor(TP::COLOR_TOOLBAR_BUTTON_ICON_HOVERED, toolbar_button_icon_color);
    SetColor(TP::COLOR_TOOLBAR_BUTTON_ICON_PRESSED, toolbar_button_icon_color);
    SetColor(TP::COLOR_TAB_THROBBER_SPINNING, toolbar_button_icon_color);
    SetColor(TP::COLOR_TAB_THROBBER_WAITING, toolbar_button_icon_color);
  } else if (GetTint(TP::TINT_BUTTONS, &button_tint)) {
    // Duplicate how COLOR_TOOLBAR_BUTTON_ICON will be computed.
    // TODO(pkasting): Should this code be shared with
    // ThemeHelper::GetDefaultColor() somehow?
    const SkColor button_color =
        color_utils::HSLShift(gfx::kGoogleGrey700, button_tint);
    SetColor(TP::COLOR_TAB_THROBBER_SPINNING, button_color);
    SetColor(TP::COLOR_TAB_THROBBER_WAITING, button_color);
  }
  SkColor toolbar_text_color;
  if (GetColor(TP::COLOR_TOOLBAR_TEXT, &toolbar_text_color)) {
    SetColorIfUnspecified(TP::COLOR_BOOKMARK_TEXT, toolbar_text_color);
    SetColorIfUnspecified(TP::COLOR_TAB_FOREGROUND_ACTIVE_FRAME_ACTIVE,
                          toolbar_text_color);
  }
  SkColor tab_foreground_color;
  if (GetColor(TP::COLOR_TAB_FOREGROUND_ACTIVE_FRAME_ACTIVE,
               &tab_foreground_color)) {
    SetColor(TP::COLOR_TAB_FOREGROUND_ACTIVE_FRAME_INACTIVE,
             tab_foreground_color);
  }
  SkColor omnibox_background_color;
  if (GetColor(TP::COLOR_OMNIBOX_BACKGROUND, &omnibox_background_color)) {
    omnibox_background_color = color_utils::GetResultingPaintColor(
        omnibox_background_color, toolbar_color);
    SetColor(TP::COLOR_OMNIBOX_BACKGROUND, omnibox_background_color);
  } else {
    // TODO(pkasting): This should be shared with the omnibox color mixer.
    omnibox_background_color = gfx::kGoogleGrey100;
  }
  SkColor omnibox_text_color;
  if (GetColor(TP::COLOR_OMNIBOX_TEXT, &omnibox_text_color)) {
    SetColor(TP::COLOR_OMNIBOX_TEXT,
             color_utils::GetResultingPaintColor(omnibox_text_color,
                                                 omnibox_background_color));
  }
}

void BrowserThemePack::CreateToolbarImageAndColors(ImageCache* images) {
  ImageCache temp_output;

  constexpr PersistentID kSrcImageId = PRS::kToolbar;

  const auto image_it = images->find(kSrcImageId);
  if (image_it == images->end()) {
    return;
  }

  auto image = image_it->second.AsImageSkia();

  constexpr int kToolbarColorId = TP::COLOR_TOOLBAR;
  SkColor toolbar_color;
  if (!GetColor(kToolbarColorId, &toolbar_color)) {
    toolbar_color = TP::GetDefaultColor(kToolbarColorId, false);
  }

  // Generate a composite image by drawing the toolbar image on top of the
  // specified toolbar color (if any).
  color_utils::HSL hsl_shift{-1, -1, -1};
  gfx::ImageSkia overlay;
  auto source = std::make_unique<TabBackgroundImageSource>(
      toolbar_color, image, overlay, hsl_shift, 0);
  gfx::Size dest_size = image.size();

  const gfx::Image dest_image(gfx::ImageSkia(std::move(source), dest_size));
  temp_output[kSrcImageId] = dest_image;

  SetColorIfUnspecified(kToolbarColorId,
                        ComputeImageColor(dest_image, dest_size.height()));

  MergeImageCaches(temp_output, images);
}

void BrowserThemePack::CreateFrameImagesAndColors(ImageCache* images) {
  static constexpr struct FrameValues {
    PersistentID prs_id;
    int tint_id;
    std::optional<int> color_id;
  } kFrameValues[] = {
      {PRS::kFrame, TP::TINT_FRAME, TP::COLOR_FRAME_ACTIVE},
      {PRS::kFrameInactive, TP::TINT_FRAME_INACTIVE, TP::COLOR_FRAME_INACTIVE},
      {PRS::kFrameOverlay, TP::TINT_FRAME, std::nullopt},
      {PRS::kFrameOverlayInactive, TP::TINT_FRAME_INACTIVE, std::nullopt},
      {PRS::kFrameIncognito, TP::TINT_FRAME_INCOGNITO,
       TP::COLOR_FRAME_ACTIVE_INCOGNITO},
      {PRS::kFrameIncognitoInactive, TP::TINT_FRAME_INCOGNITO_INACTIVE,
       TP::COLOR_FRAME_INACTIVE_INCOGNITO},
  };

  // Create all the output images in a separate cache and move them back into
  // the input images because there can be name collisions.
  ImageCache temp_output;

  for (const auto& frame_values : kFrameValues) {
    PersistentID src_id = frame_values.prs_id;
    // If the theme doesn't provide an image, attempt to fall back to one it
    // does.
    if (!images->count(src_id)) {
      // Fall back from inactive overlay to active overlay.
      if (src_id == PRS::kFrameOverlayInactive) {
        src_id = PRS::kFrameOverlay;
      }

      // Fall back from inactive incognito to active incognito.
      if (src_id == PRS::kFrameIncognitoInactive) {
        src_id = PRS::kFrameIncognito;
      }

      // For all non-overlay images, fall back to PRS_THEME_FRAME as a last
      // resort.
      if (!images->count(src_id) && src_id != PRS::kFrameOverlay) {
        src_id = PRS::kFrame;
      }
    }

    // Note that if the original ID and all the fallbacks are absent, the caller
    // will rely on the frame colors instead.
    const auto image = images->find(src_id);
    if (image != images->end()) {
      const gfx::Image dest_image(
          gfx::ImageSkiaOperations::CreateHSLShiftedImage(
              *image->second.ToImageSkia(),
              GetTintInternal(frame_values.tint_id)));

      temp_output[frame_values.prs_id] = dest_image;

      if (frame_values.color_id) {
        SetColorIfUnspecified(
            frame_values.color_id.value(),
            ComputeImageColor(dest_image, kTallestFrameHeight));
      }
    }
  }
  MergeImageCaches(temp_output, images);
}

void BrowserThemePack::GenerateFrameColorsFromTints() {
  SkColor frame;
  if (!GetColor(TP::COLOR_FRAME_ACTIVE, &frame)) {
    frame = TP::GetDefaultColor(TP::COLOR_FRAME_ACTIVE, false);
    SetColor(TP::COLOR_FRAME_ACTIVE,
             HSLShift(frame, GetTintInternal(TP::TINT_FRAME)));
  }

  SetColorIfUnspecified(
      TP::COLOR_FRAME_INACTIVE,
      HSLShift(frame, GetTintInternal(TP::TINT_FRAME_INACTIVE)));

  SetColorIfUnspecified(
      TP::COLOR_FRAME_ACTIVE_INCOGNITO,
      HSLShift(frame, GetTintInternal(TP::TINT_FRAME_INCOGNITO)));

  SetColorIfUnspecified(
      TP::COLOR_FRAME_INACTIVE_INCOGNITO,
      HSLShift(frame, GetTintInternal(TP::TINT_FRAME_INCOGNITO_INACTIVE)));
}

void BrowserThemePack::GenerateWindowControlButtonColor(ImageCache* images) {
  static constexpr struct ControlBGValue {
    // The color to compute and store.
    int color_id;

    // The frame color to use as the base of this button background.
    int frame_color_id;
  } kControlButtonBackgroundMap[] = {
      {TP::COLOR_WINDOW_CONTROL_BUTTON_BACKGROUND_ACTIVE,
       TP::COLOR_FRAME_ACTIVE},
      {TP::COLOR_WINDOW_CONTROL_BUTTON_BACKGROUND_INACTIVE,
       TP::COLOR_FRAME_INACTIVE},
      {TP::COLOR_WINDOW_CONTROL_BUTTON_BACKGROUND_INCOGNITO_ACTIVE,
       TP::COLOR_FRAME_ACTIVE_INCOGNITO},
      {TP::COLOR_WINDOW_CONTROL_BUTTON_BACKGROUND_INCOGNITO_INACTIVE,
       TP::COLOR_FRAME_INACTIVE_INCOGNITO},
  };

  // Get data related to the control button background image and color first,
  // since they are shared by all variants.
  gfx::ImageSkia bg_image;
  ImageCache::const_iterator bg_img_it =
      images->find(PRS::kWindowControlBackground);
  if (bg_img_it != images->end()) {
    bg_image = bg_img_it->second.AsImageSkia();
  }

  SkColor button_bg_color = SK_ColorTRANSPARENT;
  SkAlpha button_bg_alpha = SK_AlphaTRANSPARENT;
  if (GetColor(TP::COLOR_CONTROL_BUTTON_BACKGROUND, &button_bg_color)) {
    button_bg_alpha = SkColorGetA(button_bg_color);
  }

  button_bg_alpha =
      WindowFrameUtil::CalculateWindowsCaptionButtonBackgroundAlpha(
          button_bg_alpha);

  // Determine what portion of the image to use in our calculations (we won't
  // use more along the X-axis than the width of the caption buttons).  This
  // should theoretically be the maximum of the size of the caption button area
  // on the glass frame and opaque frame, but it would be rather complicated to
  // determine the size of the opaque frame's caption button area at pack
  // processing time (as it is determined by the size of icons, which we don't
  // have easy access to here), so we use the glass frame area as an
  // approximation.
  gfx::Size dest_size = WindowFrameUtil::GetWindowsCaptionButtonAreaSize();

  // To get an accurate sampling, all we need to do is get a representative
  // image that is at MOST the size of the caption button area.  In the case of
  // an image that is smaller - we only need to sample an area the size of the
  // provided image (trying to take tiling into account would be overkill).
  if (!bg_image.isNull()) {
    dest_size.SetToMin(bg_image.size());
  }

  for (const ControlBGValue& bg_pair : kControlButtonBackgroundMap) {
    SkColor frame_color;
    GetColor(bg_pair.frame_color_id, &frame_color);
    SkColor base_color =
        color_utils::AlphaBlend(button_bg_color, frame_color, button_bg_alpha);

    if (bg_image.isNull()) {
      SetColor(bg_pair.color_id, base_color);
      continue;
    }

    auto source = std::make_unique<ControlButtonBackgroundImageSource>(
        base_color, bg_image, dest_size);
    const gfx::Image dest_image(gfx::ImageSkia(std::move(source), dest_size));

    SetColorIfUnspecified(bg_pair.color_id,
                          ComputeImageColor(dest_image, dest_size.height()));
  }
}

void BrowserThemePack::CreateTabBackgroundImagesAndColors(ImageCache* images) {
  static constexpr struct TabValues {
    // The background image to create/update.
    PersistentID tab_id;

    // For inactive images, the corresponding active image.  If the active
    // images are customized and the inactive ones are not, the inactive ones
    // will be based on the active ones.
    std::optional<PersistentID> fallback_tab_id;

    // The frame image to use as the base of this tab background image.
    PersistentID frame_id;

    // The frame color to use as the base of this tab background image.
    int frame_color_id;

    // The color to compute and store for this image, if not present.
    int color_id;
  } kTabBackgroundMap[] = {
      {PRS::kTabBackground, std::nullopt, PRS::kFrame, TP::COLOR_FRAME_ACTIVE,
       TP::COLOR_TAB_BACKGROUND_INACTIVE_FRAME_ACTIVE},
      {PRS::kTabBackgroundInactive, PRS::kTabBackground, PRS::kFrameInactive,
       TP::COLOR_FRAME_INACTIVE,
       TP::COLOR_TAB_BACKGROUND_INACTIVE_FRAME_INACTIVE},
      {PRS::kTabBackgroundIncognito, std::nullopt, PRS::kFrameIncognito,
       TP::COLOR_FRAME_ACTIVE_INCOGNITO,
       TP::COLOR_TAB_BACKGROUND_INACTIVE_FRAME_ACTIVE_INCOGNITO},
      {PRS::kTabBackgroundIncognitoInactive, PRS::kTabBackgroundIncognito,
       PRS::kFrameIncognitoInactive, TP::COLOR_FRAME_INACTIVE_INCOGNITO,
       TP::COLOR_TAB_BACKGROUND_INACTIVE_FRAME_INACTIVE_INCOGNITO},
  };

  ImageCache temp_output;
  for (const auto& entry : kTabBackgroundMap) {
    ImageCache::const_iterator tab_it = images->find(entry.tab_id);

    // Inactive images should be based on the active ones if the active ones
    // were customized.
    if (tab_it == images->end() && entry.fallback_tab_id) {
      tab_it = images->find(*entry.fallback_tab_id);
    }

    // Generate background tab images when provided with custom frame or
    // background tab images; in the former case the theme author may want the
    // background tabs to appear to tint the frame, and in the latter case the
    // provided background tab image may have transparent regions, which must be
    // made opaque by overlaying atop the original frame.
    const ImageCache::const_iterator frame_it = images->find(entry.frame_id);
    if (frame_it != images->end() || tab_it != images->end()) {
      SkColor frame_color;
      GetColor(entry.frame_color_id, &frame_color);

      gfx::ImageSkia image_to_tint;
      if (frame_it != images->end()) {
        image_to_tint = (frame_it->second).AsImageSkia();
      }

      gfx::ImageSkia overlay;
      if (tab_it != images->end()) {
        overlay = tab_it->second.AsImageSkia();
      }

      auto source = std::make_unique<TabBackgroundImageSource>(
          frame_color, image_to_tint, overlay,
          GetTintInternal(TP::TINT_BACKGROUND_TAB), TP::kFrameHeightAboveTabs);
      gfx::Size dest_size = image_to_tint.size();
      dest_size.SetToMax(overlay.size());
      dest_size.set_height(kTallestTabHeight);
      const gfx::Image dest_image(gfx::ImageSkia(std::move(source), dest_size));
      temp_output[entry.tab_id] = dest_image;

      SetColorIfUnspecified(entry.color_id,
                            ComputeImageColor(dest_image, kTallestTabHeight));
    }
  }
  MergeImageCaches(temp_output, images);
}

void BrowserThemePack::GenerateMissingNtpColors() {
  gfx::Image image = GetImageNamed(IDR_THEME_NTP_BACKGROUND);
  bool has_background_image = !image.IsEmpty();

  // Opaquify background color.
  SkColor background_color;
  bool has_background_color =
      GetColor(TP::COLOR_NTP_BACKGROUND, &background_color);
  if (has_background_color) {
    background_color = color_utils::GetResultingPaintColor(
        background_color, TP::GetDefaultColor(TP::COLOR_NTP_BACKGROUND, false));
    SetColor(TP::COLOR_NTP_BACKGROUND, background_color);
  }

  // Calculate NTP text color based on NTP background.
  SkColor text_color;
  if (!GetColor(TP::COLOR_NTP_TEXT, &text_color)) {
    if (has_background_image) {
      background_color = ComputeImageColor(image, image.Height());
    }

    if (has_background_image || has_background_color) {
      SetColor(TP::COLOR_NTP_TEXT,
               color_utils::GetColorWithMaxContrast(background_color));
    }
  }

  // Calculate logo alternate, if not specified.
  int logo_alternate = 0;
  if (!GetDisplayProperty(TP::NTP_LOGO_ALTERNATE, &logo_alternate)) {
    logo_alternate =
        has_background_image ||
        (has_background_color && !IsColorGrayscale(background_color));
    SetDisplayProperty(TP::NTP_LOGO_ALTERNATE, logo_alternate);
  }

  // For themes that use alternate logo and no NTP background image is present,
  // set logo color in the same hue as NTP background.
  if (logo_alternate == 1 && !has_background_image && has_background_color) {
    SkColor logo_color = color_utils::IsDark(background_color)
                             ? SK_ColorWHITE
                             : GetContrastingColor(background_color,
                                                   /*luminosity_change=*/0.3f);
    SetColor(TP::COLOR_NTP_LOGO, logo_color);
  }

  // Calculate NTP section border color.
  SkColor header_color;
  if (GetColor(TP::COLOR_NTP_HEADER, &header_color)) {
    SetColor(TP::COLOR_NTP_SECTION_BORDER, SkColorSetA(header_color, 0x50));
  }
}

void BrowserThemePack::RepackImages(const ImageCache& images,
                                    RawImages* reencoded_images) const {
  for (const auto& image : images) {
    gfx::ImageSkia image_skia = *image.second.ToImageSkia();

    std::vector<gfx::ImageSkiaRep> image_reps = image_skia.image_reps();
    DCHECK(!image_reps.empty())
        << "No image reps for resource " << image.first << ".";
    for (const auto& rep : image_reps) {
      std::optional<std::vector<uint8_t>> bitmap_data =
          gfx::PNGCodec::EncodeBGRASkBitmap(rep.GetBitmap(),
                                            /*discard_transparency=*/false);
      CHECK(bitmap_data) << "Image file for resource " << image.first
                         << " could not be encoded.";
      int raw_id = GetRawIDByPersistentID(
          image.first, ui::GetSupportedResourceScaleFactor(rep.scale()));
      (*reencoded_images)[raw_id] = base::MakeRefCounted<base::RefCountedBytes>(
          std::move(bitmap_data).value());
    }
  }
}

void BrowserThemePack::MergeImageCaches(const ImageCache& source,
                                        ImageCache* destination) const {
  for (const auto& it : source) {
    (*destination)[it.first] = it.second;
  }
}

void BrowserThemePack::AddRawImagesTo(const RawImages& images,
                                      RawDataForWriting* out) const {
  for (const auto& pair : images) {
    (*out)[pair.first] = base::as_string_view(*pair.second);
  }
}

color_utils::HSL BrowserThemePack::GetTintInternal(int id) const {
  color_utils::HSL hsl;
  if (GetTint(id, &hsl)) {
    return hsl;
  }

  int original_id = id;
  if (id == TP::TINT_FRAME_INCOGNITO) {
    original_id = TP::TINT_FRAME;
  } else if (id == TP::TINT_FRAME_INCOGNITO_INACTIVE) {
    original_id = TP::TINT_FRAME_INACTIVE;
  }

  return TP::GetDefaultTint(original_id, original_id != id);
}

int BrowserThemePack::GetRawIDByPersistentID(
    PersistentID prs_id,
    ui::ResourceScaleFactor scale_factor) const {
  if (prs_id == PersistentID::kInvalid) {
    return -1;
  }

  for (size_t i = 0; i < scale_factors_.size(); ++i) {
    if (scale_factors_[i] == scale_factor) {
      return ((PersistentID::kMaxValue + 1) * i) + prs_id;
    }
  }
  return -1;
}

bool BrowserThemePack::GetScaleFactorFromManifestKey(
    const std::string& key,
    ui::ResourceScaleFactor* scale_factor) const {
  int percent = 0;
  if (base::StringToInt(key, &percent)) {
    float scale = static_cast<float>(percent) / 100.0f;
    for (auto i : scale_factors_) {
      if (fabs(ui::GetScaleForResourceScaleFactor(i) - scale) < 0.001) {
        *scale_factor = i;
        return true;
      }
    }
  }
  return false;
}

void BrowserThemePack::GenerateRawImageForAllSupportedScales(
    PersistentID prs_id) {
  // Compute (by scaling) bitmaps for |prs_id| for any scale factors
  // for which the theme author did not provide a bitmap. We compute
  // the bitmaps using the highest scale factor that theme author
  // provided.
  // Note: We use only supported scale factors. For example, if scale
  // factor 2x is supported by the current system, but 1.8x is not and
  // if the theme author did not provide an image for 2x but one for
  // 1.8x, we will not use the 1.8x image here. Here we will only use
  // images provided for scale factors supported by the current system.

  // See if any image is missing. If not, we're done.
  bool image_missing = false;
  for (auto& scale_factor : scale_factors_) {
    int raw_id = GetRawIDByPersistentID(prs_id, scale_factor);
    if (image_memory_.find(raw_id) == image_memory_.end()) {
      image_missing = true;
      break;
    }
  }
  if (!image_missing) {
    return;
  }

  // Find available scale factor with highest scale.
  ui::ResourceScaleFactor available_scale_factor = ui::kScaleFactorNone;
  for (auto& scale_factor : scale_factors_) {
    int raw_id = GetRawIDByPersistentID(prs_id, scale_factor);
    if ((available_scale_factor == ui::kScaleFactorNone ||
         (ui::GetScaleForResourceScaleFactor(scale_factor) >
          ui::GetScaleForResourceScaleFactor(available_scale_factor))) &&
        image_memory_.find(raw_id) != image_memory_.end()) {
      available_scale_factor = scale_factor;
    }
  }
  // If no scale factor is available, we're done.
  if (available_scale_factor == ui::kScaleFactorNone) {
    return;
  }

  // Get bitmap for the available scale factor.
  int available_raw_id = GetRawIDByPersistentID(prs_id, available_scale_factor);
  RawImages::const_iterator it = image_memory_.find(available_raw_id);
  SkBitmap available_bitmap = gfx::PNGCodec::Decode(*it->second);
  if (available_bitmap.isNull()) {
    // The image is either broken or a different format.
    return;
  }

  // Fill in all missing scale factors by scaling the available bitmap.
  for (auto& scale_factor : scale_factors_) {
    int scaled_raw_id = GetRawIDByPersistentID(prs_id, scale_factor);
    if (image_memory_.find(scaled_raw_id) != image_memory_.end()) {
      continue;
    }
    SkBitmap scaled_bitmap = CreateLowQualityResizedBitmap(
        available_bitmap, available_scale_factor, scale_factor);
    std::optional<std::vector<uint8_t>> bitmap_data =
        gfx::PNGCodec::EncodeBGRASkBitmap(scaled_bitmap,
                                          /*discard_transparency=*/false);
    if (!bitmap_data) {
      NOTREACHED() << "Unable to encode theme image for prs_id=" << prs_id
                   << " for scale_factor=" << scale_factor;
    }
    image_memory_[scaled_raw_id] = base::MakeRefCounted<base::RefCountedBytes>(
        std::move(bitmap_data).value());
  }
}