File: chrome_browser_application_mac.mm

package info (click to toggle)
chromium 138.0.7204.157-1
  • links: PTS, VCS
  • area: main
  • in suites: sid, trixie
  • size: 6,071,864 kB
  • sloc: cpp: 34,936,859; ansic: 7,176,967; javascript: 4,110,704; python: 1,419,953; asm: 946,768; xml: 739,967; pascal: 187,324; sh: 89,623; perl: 88,663; objc: 79,944; sql: 50,304; cs: 41,786; fortran: 24,137; makefile: 21,806; php: 13,980; tcl: 13,166; yacc: 8,925; ruby: 7,485; awk: 3,720; lisp: 3,096; lex: 1,327; ada: 727; jsp: 228; sed: 36
file content (576 lines) | stat: -rw-r--r-- 23,175 bytes parent folder | download | duplicates (3)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
// 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.

#import "chrome/browser/chrome_browser_application_mac.h"

#include <Carbon/Carbon.h>  // for <HIToolbox/Events.h>

#include "base/apple/call_with_eh_frame.h"
#include "base/check.h"
#include "base/command_line.h"
#import "base/mac/mac_util.h"
#include "base/observer_list.h"
#include "base/strings/stringprintf.h"
#include "base/strings/sys_string_conversions.h"
#include "base/trace_event/trace_event.h"
#import "chrome/browser/app_controller_mac.h"
#import "chrome/browser/mac/exception_processor.h"
#include "chrome/browser/ui/cocoa/l10n_util.h"
#include "chrome/common/chrome_switches.h"
#include "components/crash/core/common/crash_key.h"
#import "components/crash/core/common/objc_zombie.h"
#include "content/public/browser/browser_accessibility_state.h"
#include "content/public/browser/native_event_processor_mac.h"
#include "content/public/browser/native_event_processor_observer_mac.h"
#include "content/public/browser/scoped_accessibility_mode.h"
#include "content/public/common/content_features.h"
#include "ui/accessibility/ax_mode.h"
#include "ui/base/cocoa/accessibility_focus_overrider.h"

namespace chrome_browser_application_mac {

void RegisterBrowserCrApp() {
  [BrowserCrApplication sharedApplication];

  // If there was an invocation to NSApp prior to this method, then the NSApp
  // will not be a BrowserCrApplication, but will instead be an NSApplication.
  // This is undesirable and we must enforce that this doesn't happen.
  CHECK([NSApp isKindOfClass:[BrowserCrApplication class]]);
}

void InitializeHeadlessMode() {
  // In headless mode the browser window exists but is always hidden, so there
  // is no point in showing dock icon and menu bar.
  NSApp.activationPolicy = NSApplicationActivationPolicyAccessory;
}

void Terminate() {
  [NSApp terminate:nil];
}

void CancelTerminate() {
  [NSApp cancelTerminate:nil];
}

}  // namespace chrome_browser_application_mac

namespace {

// Calling -[NSEvent description] is rather slow to build up the event
// description. The description is stored in a crash key to aid debugging, so
// this helper function constructs a shorter, but still useful, description.
// See <https://crbug.com/770405>.
std::string DescriptionForNSEvent(NSEvent* event) {
  std::string desc = base::StringPrintf(
      "NSEvent type=%ld modifierFlags=0x%lx locationInWindow=(%g,%g)",
      event.type, event.modifierFlags, event.locationInWindow.x,
      event.locationInWindow.y);
  switch (event.type) {
    case NSEventTypeKeyDown:
    case NSEventTypeKeyUp: {
      // Some NSEvents return a string with NUL in event.characters, see
      // <https://crbug.com/826908>. To make matters worse, in rare cases,
      // NSEvent.characters or NSEvent.charactersIgnoringModifiers can throw an
      // NSException complaining that "TSMProcessRawKeyCode failed". Since we're
      // trying to gather a crash key here, if that exception happens, just
      // remark that it happened and continue rather than crashing the browser.
      std::string characters, unmodified_characters;
      @try {
        characters = base::SysNSStringToUTF8([event.characters
            stringByReplacingOccurrencesOfString:@"\0"
                                      withString:@"\\x00"]);
        unmodified_characters =
            base::SysNSStringToUTF8([event.charactersIgnoringModifiers
                stringByReplacingOccurrencesOfString:@"\0"
                                          withString:@"\\x00"]);
      } @catch (id exception) {
        characters = "(exception)";
        unmodified_characters = "(exception)";
      }
      desc += base::StringPrintf(
          " keyCode=0x%d ARepeat=%d characters='%s' unmodifiedCharacters='%s'",
          event.keyCode, event.ARepeat, characters.c_str(),
          unmodified_characters.c_str());
      break;
    }
    case NSEventTypeLeftMouseDown:
    case NSEventTypeLeftMouseDragged:
    case NSEventTypeLeftMouseUp:
    case NSEventTypeOtherMouseDown:
    case NSEventTypeOtherMouseDragged:
    case NSEventTypeOtherMouseUp:
    case NSEventTypeRightMouseDown:
    case NSEventTypeRightMouseDragged:
    case NSEventTypeRightMouseUp:
      desc += base::StringPrintf(" buttonNumber=%ld clickCount=%ld",
                                 event.buttonNumber, event.clickCount);
      break;
    case NSEventTypeAppKitDefined:
    case NSEventTypeSystemDefined:
    case NSEventTypeApplicationDefined:
    case NSEventTypePeriodic:
      desc += base::StringPrintf(" subtype=%d data1=%ld data2=%ld",
                                 event.subtype, event.data1, event.data2);
      break;
    default:
      break;
  }
  return desc;
}

}  // namespace

@interface BrowserCrApplication () <NativeEventProcessor> {
  // A counter for enhanced user interface enable (+1) and disable (-1)
  // requests.
  int _AXEnhancedUserInterfaceRequests;
  BOOL _voiceOverEnabled;
  BOOL _sonomaAccessibilityRefinementsAreActive;
}

// Enables/disables screen reader support on changes to VoiceOver status.
- (void)voiceOverStateChanged:(BOOL)voiceOverEnabled;
@end

@implementation BrowserCrApplication {
  base::ObserverList<content::NativeEventProcessorObserver>::Unchecked
      _observers;
  BOOL _handlingSendEvent;
  std::unique_ptr<content::ScopedAccessibilityMode>
      _scoped_accessibility_mode_voiceover;
  std::unique_ptr<content::ScopedAccessibilityMode>
      _scoped_accessibility_mode_general;
}

+ (void)initialize {
  if (self != [BrowserCrApplication class]) {
    return;
  }
  InstallObjcExceptionPreprocessor();

  cocoa_l10n_util::ApplyForcedRTL();
}

- (void)orderFrontCharacterPalette:sender {
  [[NSNotificationCenter defaultCenter]
      postNotificationName:@"ChromeWillOrderFrontCharacterPalette"
                    object:nil];

  [super orderFrontCharacterPalette:sender];
}

// Initialize NSApplication using the custom subclass.  Check whether NSApp
// was already initialized using another class, because that would break
// some things.
+ (NSApplication*)sharedApplication {
  NSApplication* app = [super sharedApplication];

  // +sharedApplication initializes the global NSApp, so if a specific
  // NSApplication subclass is requested, require that to be the one
  // delivered.  The practical effect is to require a consistent NSApp
  // across the executable.
  CHECK([NSApp isKindOfClass:self])
      << "NSApp must be of type " << [[self className] UTF8String]
      << ", not " << [[NSApp className] UTF8String];

  // If the message loop was initialized before NSApp is setup, the
  // message pump will be setup incorrectly.  Failing this implies
  // that RegisterBrowserCrApp() should be called earlier.
  CHECK(base::message_pump_apple::UsingCrApp())
      << "message_pump_apple::Create() is using the wrong pump implementation"
      << " for " << [[self className] UTF8String];

  return app;
}

- (void)finishLaunching {
  [super finishLaunching];

  // The accessibility feature, enabled from Finch, should already be
  // restricted to macOS 14, but we'll make an additional check here in the
  // code.
  _sonomaAccessibilityRefinementsAreActive =
      base::mac::MacOSVersion() >= 14'00'00 &&
      base::FeatureList::IsEnabled(
          features::kSonomaAccessibilityActivationRefinements);
}

- (void)observeValueForKeyPath:(NSString*)keyPath
                      ofObject:(id)object
                        change:(NSDictionary*)change
                       context:(void*)context {
  // KVO of the system's VoiceOver state gets set up during initialization of
  // BrowserAccessibilityStateImplMac. The context is the browser's
  // global accessibility object, which we must check to ensure we're acting
  // on a notification we set up (vs. NSApplication, say).
  if ([keyPath isEqualToString:@"voiceOverEnabled"] &&
      context == content::BrowserAccessibilityState::GetInstance()) {
    NSNumber* newValueNumber = [change objectForKey:NSKeyValueChangeNewKey];

    // In the if statement below, we check newValueNumber's class before
    // accessing it to guard against crashes should the return type suddenly
    // change in the future. We DCHECK here to flag any such change.
    DCHECK([newValueNumber isKindOfClass:[NSNumber class]]);

    if ([newValueNumber isKindOfClass:[NSNumber class]]) {
      [self voiceOverStateChanged:[newValueNumber boolValue]];
    }

    return;
  }

  [super observeValueForKeyPath:keyPath
                       ofObject:object
                         change:change
                        context:context];
}

// AppKit menu customization overriding

- (void)_customizeFileMenuIfNeeded {
  // Whenever the main menu is set or modified, AppKit modifies it before using
  // it. AppKit calls -[NSApplication _customizeMainMenu], which calls out to a
  // number of customization methods, including -[NSApplication
  // _customizeFileMenuIfNeeded].
  //
  // -_customizeFileMenuIfNeeded does three things:
  //   1. it adds the "Close All" menu item as an alternate for "Close Window",
  //   2. for new-style document apps, it turns "Save" and "Save As..." into
  //      "Save..." and "Duplicate" respectively,
  //   3. depending on the "Close windows when quitting an application" system
  //      setting, it adds either "Quit and Keep Windows" or "Quit and Close All
  //      Windows" as an alternate for "Quit Chromium".
  //
  // While #1 is a nice-to-have, and #2 is irrelevant because Chromium isn't a
  // new-style document app, #3 is a problem. Chromium has its own session
  // management, and the menu item alternates that AppKit adds are making
  // promises that Chromium can't fulfill.
  //
  // Therefore, override this method to prevent AppKit from doing these menu
  // shenanigans. For #1, "Close All" is explicitly added to the File menu in
  // main_menu_builder.mm, and there is nothing lost by preventing the other
  // two.
  return;
}

////////////////////////////////////////////////////////////////////////////////
// HISTORICAL COMMENT (by viettrungluu, from
// http://codereview.chromium.org/1520006 with mild editing):
//
// A quick summary of the state of things (before the changes to shutdown):
//
// Currently, we are totally hosed (put in a bad state in which Cmd-W does the
// wrong thing, and which will probably eventually lead to a crash) if we begin
// quitting but termination is aborted for some reason.
//
// I currently know of two ways in which termination can be aborted:
// (1) Common case: a window has an onbeforeunload handler which pops up a
//     "leave web page" dialog, and the user answers "no, don't leave".
// (2) Uncommon case: popups are enabled (in Content Settings, i.e., the popup
//     blocker is disabled), and some nasty web page pops up a new window on
//     closure.
//
// I don't know of other ways in which termination can be aborted, but they may
// exist (or may be added in the future, for that matter).
//
// My CL [see above] does the following:
// a. Should prevent being put in a bad state (which breaks Cmd-W and leads to
//    crash) under all circumstances.
// b. Should completely handle (1) properly.
// c. Doesn't (yet) handle (2) properly and puts it in a weird state (but not
//    that bad).
// d. Any other ways of aborting termination would put it in that weird state.
//
// c. can be fixed by having the global flag reset on browser creation or
// similar (and doing so might also fix some possible d.'s as well). I haven't
// done this yet since I haven't thought about it carefully and since it's a
// corner case.
//
// The weird state: a state in which closing the last window quits the browser.
// This might be a bit annoying, but it's not dangerous in any way.
////////////////////////////////////////////////////////////////////////////////

// |-terminate:| is the entry point for orderly "quit" operations in Cocoa. This
// includes the application menu's quit menu item and keyboard equivalent, the
// application's dock icon menu's quit menu item, "quit" (not "force quit") in
// the Activity Monitor, and quits triggered by user logout and system restart
// and shutdown.
//
// The default |-terminate:| implementation ends the process by calling exit(),
// and thus never leaves the main run loop. This is unsuitable for Chrome since
// Chrome depends on leaving the main run loop to perform an orderly shutdown.
// We support the normal |-terminate:| interface by overriding the default
// implementation. Our implementation, which is very specific to the needs of
// Chrome, works by asking the application delegate to terminate using its
// |-tryToTerminateApplication:| method.
//
// |-tryToTerminateApplication:| differs from the standard
// |-applicationShouldTerminate:| in that no special event loop is run in the
// case that immediate termination is not possible (e.g., if dialog boxes
// allowing the user to cancel have to be shown). Instead, this method sets a
// flag and tries to close all browsers. This flag causes the closure of the
// final browser window to begin actual tear-down of the application.
// Termination is cancelled by resetting this flag. The standard
// |-applicationShouldTerminate:| is not supported, and code paths leading to it
// must be redirected.
//
// When the last browser has been destroyed, the BrowserList calls
// chrome::OnAppExiting(), which is the point of no return. That will cause
// the NSApplicationWillTerminateNotification to be posted, which ends the
// NSApplication event loop, so final post- MessageLoop::Run() work is done
// before exiting.
- (void)terminate:(id)sender {
  [AppController.sharedController tryToTerminateApplication:self];
  // Return, don't exit. The application is responsible for exiting on its own.
}

- (void)cancelTerminate:(id)sender {
  [AppController.sharedController stopTryingToTerminateApplication:self];
}

- (NSEvent*)nextEventMatchingMask:(NSEventMask)mask
                        untilDate:(NSDate*)expiration
                           inMode:(NSString*)mode
                          dequeue:(BOOL)dequeue {
  __block NSEvent* event = nil;
  base::apple::CallWithEHFrame(^{
    event = [super nextEventMatchingMask:mask
                               untilDate:expiration
                                  inMode:mode
                                 dequeue:dequeue];
  });
  return event;
}

- (BOOL)sendAction:(SEL)anAction to:(id)aTarget from:(id)sender {
  // The Dock menu contains an automagic section where you can select
  // amongst open windows.  If a window is closed via JavaScript while
  // the menu is up, the menu item for that window continues to exist.
  // When a window is selected this method is called with the
  // now-freed window as |aTarget|.  Short-circuit the call if
  // |aTarget| is not a valid window.
  if (anAction == @selector(_selectWindow:)) {
    // Not using -[NSArray containsObject:] because |aTarget| may be a
    // freed object.
    BOOL found = NO;
    for (NSWindow* window in [self windows]) {
      if (window == aTarget) {
        found = YES;
        break;
      }
    }
    if (!found) {
      return NO;
    }
  }

  // When a Cocoa control is wired to a freed object, we get crashers
  // in the call to |super| with no useful information in the
  // backtrace.  Attempt to add some useful information.

  // If the action is something generic like -commandDispatch:, then
  // the tag is essential.
  NSInteger tag = 0;
  if ([sender isKindOfClass:[NSControl class]]) {
    tag = [sender tag];
    if (tag == 0 || tag == -1) {
      tag = [sender selectedTag];
    }
  } else if ([sender isKindOfClass:[NSMenuItem class]]) {
    tag = [sender tag];
  }

  NSString* actionString = NSStringFromSelector(anAction);
  std::string value = base::StringPrintf("%s tag %ld sending %s to %p",
      [[sender className] UTF8String],
      static_cast<long>(tag),
      [actionString UTF8String],
      aTarget);

  static crash_reporter::CrashKeyString<256> sendActionKey("sendaction");
  crash_reporter::ScopedCrashKeyString scopedKey(&sendActionKey, value);

  __block BOOL rv;
  base::apple::CallWithEHFrame(^{
    rv = [super sendAction:anAction to:aTarget from:sender];
  });
  return rv;
}

- (BOOL)isHandlingSendEvent {
  return _handlingSendEvent;
}

- (void)setHandlingSendEvent:(BOOL)handlingSendEvent {
  _handlingSendEvent = handlingSendEvent;
}

- (void)sendEvent:(NSEvent*)event {
  TRACE_EVENT0("toplevel", "BrowserCrApplication::sendEvent");

  // TODO(bokan): Tracing added temporarily to diagnose crbug.com/1039833.
  TRACE_EVENT_INSTANT1("toplevel", "KeyWindow", TRACE_EVENT_SCOPE_THREAD,
                       "KeyWin", [[NSApp keyWindow] windowNumber]);

  static crash_reporter::CrashKeyString<256> nseventKey("nsevent");
  crash_reporter::ScopedCrashKeyString scopedKey(&nseventKey,
                                                 DescriptionForNSEvent(event));

  base::apple::CallWithEHFrame(^{
    static const bool kKioskMode =
        base::CommandLine::ForCurrentProcess()->HasSwitch(switches::kKioskMode);
    if (kKioskMode) {
      // In kiosk mode, we want to prevent context menus from appearing,
      // so simply discard menu-generating events instead of passing them
      // along.
      BOOL couldTriggerContextMenu =
          event.type == NSEventTypeRightMouseDown ||
          (event.type == NSEventTypeLeftMouseDown &&
           (event.modifierFlags & NSEventModifierFlagControl));
      if (couldTriggerContextMenu)
        return;
    }
    base::mac::ScopedSendingEvent sendingEventScoper;
    content::ScopedNotifyNativeEventProcessorObserver scopedObserverNotifier(
        &self->_observers, event);
    // Mac Eisu and Kana keydown events are by default swallowed by sendEvent
    // and sent directly to IME, which prevents ui keydown events from firing.
    // These events need to be sent to [NSApp keyWindow] for handling.
    if (event.type == NSEventTypeKeyDown &&
        (event.keyCode == kVK_JIS_Eisu || event.keyCode == kVK_JIS_Kana)) {
      [NSApp.keyWindow sendEvent:event];
    } else {
      [super sendEvent:event];
    }
  });
}

// Accessibility Support

- (void)enableScreenReaderCompleteMode:(BOOL)enable {
  if (enable) {
    if (!_scoped_accessibility_mode_voiceover) {
      _scoped_accessibility_mode_voiceover =
          content::BrowserAccessibilityState::GetInstance()
              ->CreateScopedModeForProcess(ui::kAXModeComplete |
                                           ui::AXMode::kFromPlatform |
                                           ui::AXMode::kScreenReader);
    }
  } else {
    _scoped_accessibility_mode_voiceover.reset();
  }
}

// We need to call enableScreenReaderCompleteMode:YES from performSelector:...
// but there's no way to supply a BOOL as a parameter, so we have this
// explicit enable... helper method.
- (void)enableScreenReaderCompleteMode {
  _AXEnhancedUserInterfaceRequests = 0;
  [self enableScreenReaderCompleteMode:YES];
}

- (void)voiceOverStateChanged:(BOOL)voiceOverEnabled {
  _voiceOverEnabled = voiceOverEnabled;

  [self enableScreenReaderCompleteMode:voiceOverEnabled];
}

- (BOOL)voiceOverStateForTesting {
  return _voiceOverEnabled;
}

// Enables or disables screen reader support for non-VoiceOver assistive
// technology (AT), possibly after a delay.
//
// Now that we directly monitor VoiceOver status, we no longer watch for
// changes to AXEnhancedUserInterface for that signal from VO. However, other
// AT can set a value for AXEnhancedUserInterface, so we can't ignore it.
// Unfortunately, as of macOS Sonoma, we sometimes see spurious changes to
// AXEnhancedUserInterface (quick on and off). We debounce by waiting for these
// changes to settle down before updating the screen reader state.
- (void)enableScreenReaderCompleteModeAfterDelay:(BOOL)enable {
  // If VoiceOver is already explicitly enabled, ignore requests from other AT.
  if (_voiceOverEnabled) {
    return;
  }

  // If this is a request to disable screen reader support, and we haven't seen
  // a corresponding enable request, go ahead and disable.
  if (!enable && _AXEnhancedUserInterfaceRequests == 0) {
    [self enableScreenReaderCompleteMode:NO];
    return;
  }

  // Use a counter to track requests for changes to the screen reader state.
  if (enable) {
    _AXEnhancedUserInterfaceRequests++;
  } else {
    _AXEnhancedUserInterfaceRequests--;
  }

  DCHECK(_AXEnhancedUserInterfaceRequests >= 0);

  // _AXEnhancedUserInterfaceRequests > 0 means we want to enable screen
  // reader support, but we'll delay that action until there are no more state
  // change requests within a two-second window. Cancel any pending
  // performSelector:..., and schedule a new one to restart the countdown.
  [NSObject cancelPreviousPerformRequestsWithTarget:self
                                           selector:@selector
                                           (enableScreenReaderCompleteMode)
                                             object:nil];

  if (_AXEnhancedUserInterfaceRequests > 0) {
    const float kTwoSecondDelay = 2.0;
    [self performSelector:@selector(enableScreenReaderCompleteMode)
               withObject:nil
               afterDelay:kTwoSecondDelay];
  }
}

- (void)accessibilitySetValue:(id)value forAttribute:(NSString*)attribute {
  // This is an undocumented attribute that's set when VoiceOver is turned
  // on/off. We track VoiceOver state changes using KVO, but monitor this
  // attribute in case other ATs use it to request accessibility activation.
  if ([attribute isEqualToString:@"AXEnhancedUserInterface"]) {
    [self enableScreenReaderCompleteModeAfterDelay:[value boolValue]];
  }
  return [super accessibilitySetValue:value forAttribute:attribute];
}

- (id)accessibilityFocusedUIElement {
  if (id forced_focus = ui::AccessibilityFocusOverrider::GetFocusedUIElement())
    return forced_focus;
  return [super accessibilityFocusedUIElement];
}

- (NSAccessibilityRole)accessibilityRole {
  // For non-VoiceOver assistive technology (AT), such as Voice Control, Apple
  // recommends turning on a11y when an AT accesses the 'accessibilityRole'
  // property. This function is accessed frequently, so we only change the
  // accessibility state when accessibility is already disabled.
  if (!_scoped_accessibility_mode_general &&
      !_scoped_accessibility_mode_voiceover) {
    ui::AXMode target_mode = _sonomaAccessibilityRefinementsAreActive
                                 ? ui::AXMode::kNativeAPIs
                                 : ui::kAXModeBasic;
    _scoped_accessibility_mode_general =
        content::BrowserAccessibilityState::GetInstance()
            ->CreateScopedModeForProcess(target_mode |
                                         ui::AXMode::kFromPlatform);
  }

  return [super accessibilityRole];
}

- (void)addNativeEventProcessorObserver:
    (content::NativeEventProcessorObserver*)observer {
  _observers.AddObserver(observer);
}

- (void)removeNativeEventProcessorObserver:
    (content::NativeEventProcessorObserver*)observer {
  _observers.RemoveObserver(observer);
}

@end