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// Copyright 2021 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef CONTENT_BROWSER_ACCESSIBILITY_RENDER_ACCESSIBILITY_HOST_H_
#define CONTENT_BROWSER_ACCESSIBILITY_RENDER_ACCESSIBILITY_HOST_H_
#include <vector>
#include "base/memory/weak_ptr.h"
#include "content/public/browser/global_routing_id.h"
#include "mojo/public/cpp/bindings/pending_receiver.h"
#include "mojo/public/cpp/bindings/receiver_set.h"
#include "mojo/public/cpp/bindings/self_owned_receiver.h"
#include "third_party/blink/public/mojom/render_accessibility.mojom.h"
#include "ui/accessibility/ax_location_and_scroll_updates.h"
#include "ui/accessibility/ax_tree_id.h"
#include "ui/accessibility/mojom/ax_updates_and_events.mojom.h"
namespace content {
class RenderFrameHostImpl;
// Handles accessibility messages sent from the renderer to the browser possibly
// off the main UI thread and then forwards them to the RenderFrameHostImpl on
// the browser process main thread, so that the potentially large
// deserialization does not block the main thread.
//
// This endpoint is bound on the ThreadPool for *performance reasons*, so its
// messages can be reordered w.r.t. navigation. To mitigate this:
//
// * The renderer explicitly destroys this endpoint when committing a new
// document in the existing RenderFrame, so all messages send on behalf of a
// new document will go through new document's BrowserInterfaceBroker.
//
// * Each message contains the per-document tree_id and the message will be
// ignored if the tree_id doesn't match the current tree_id passed at
// construction time. (It will also be checked again on the UI thread).
class RenderAccessibilityHost : public blink::mojom::RenderAccessibilityHost {
public:
RenderAccessibilityHost(
base::WeakPtr<RenderFrameHostImpl> render_frame_host_impl,
ui::AXTreeID tree_id);
void Bind(
mojo::PendingReceiver<blink::mojom::RenderAccessibilityHost> receiver) {
receiver_.Add(this, std::move(receiver));
}
RenderAccessibilityHost(const RenderAccessibilityHost&) = delete;
RenderAccessibilityHost& operator=(const RenderAccessibilityHost&) = delete;
~RenderAccessibilityHost() override;
// Sets the current state of the "renderer serialization only" variant of the
// accessibility performance measurement experiment. When enabled, all
// instances silently ignore inbound calls to `HandleAXEvents()` and
// `HandleAXLocationChanges()` from renderers.
static void SetRendererSerializationExperimentEnabled(bool enabled);
void HandleAXEvents(
const ui::AXUpdatesAndEvents& updates_and_events,
const ui::AXLocationAndScrollUpdates& location_and_scroll_updates,
uint32_t reset_token,
HandleAXEventsCallback callback) override;
void HandleAXEvents(
ui::AXUpdatesAndEvents& updates_and_events,
ui::AXLocationAndScrollUpdates& location_and_scroll_updates,
uint32_t reset_token,
HandleAXEventsCallback callback) override;
void HandleAXLocationChanges(const ui::AXLocationAndScrollUpdates& changes,
uint32_t reset_token) override;
void HandleAXLocationChanges(ui::AXLocationAndScrollUpdates& changes,
uint32_t reset_token) override;
private:
base::WeakPtr<RenderFrameHostImpl> render_frame_host_impl_;
// TODO(chrishtr): change this back to a Receiver once all render process
/// callsites of this mojo interface have been migrated to Blink.
mojo::ReceiverSet<blink::mojom::RenderAccessibilityHost> receiver_;
const ui::AXTreeID tree_id_;
};
} // namespace content
#endif // CONTENT_BROWSER_ACCESSIBILITY_RENDER_ACCESSIBILITY_HOST_H_
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