Disable accessibility when VoiceOver is turned off.

chrome/browser/chrome_browser_application_mac.mm

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // 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"
 
 #import "base/auto_reset.h"
 #include "base/debug/crash_logging.h"
 #include "base/debug/stack_trace.h"
 #import "base/logging.h"
@@ skipping 520 matching lines @@
     }
     trackedFirstException = YES;
 
     reportingException = NO;
   }
 
   [super reportException:anException];
 }
 
 - (void)accessibilitySetValue:(id)value forAttribute:(NSString*)attribute {
-  if ([attribute isEqualToString:@"AXEnhancedUserInterface"] &&
-      [value intValue] == 1) {
-    content::BrowserAccessibilityState::GetInstance()->OnScreenReaderDetected();
+  // This is an undocument attribute that's set when VoiceOver is turned on/off.
+  if ([attribute isEqualToString:@"AXEnhancedUserInterface"]) {
+    content::BrowserAccessibilityState* accessibility_state =
+        content::BrowserAccessibilityState::GetInstance();
+    if ([value intValue] == 1)
+      accessibility_state->OnScreenReaderDetected();
+    else
+      accessibility_state->DisableAccessibility();
   }
   return [super accessibilitySetValue:value forAttribute:attribute];
 }
 
 - (void)_cycleWindowsReversed:(BOOL)arg1 {
   base::AutoReset<BOOL> pin(&cyclingWindows_, YES);
   [super _cycleWindowsReversed:arg1];
 }
 
 - (BOOL)isCyclingWindows {
@@ skipping 49 matching lines @@
   std::vector<NSWindow*>::iterator window_iterator =
       std::find(previousKeyWindows_.begin(),
                 previousKeyWindows_.end(),
                 window);
   if (window_iterator != previousKeyWindows_.end()) {
     previousKeyWindows_.erase(window_iterator);
   }
 }
 
 @end