Suppress accessibility events when user is navigating away.

content/browser/accessibility/browser_accessibility_manager_win.cc

 // 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.
 
 #include "content/browser/accessibility/browser_accessibility_manager_win.h"
 
 #include "base/command_line.h"
 #include "base/win/scoped_comptr.h"
 #include "base/win/windows_version.h"
 #include "content/browser/accessibility/browser_accessibility_state_impl.h"
@@ skipping 114 matching lines @@
     NotifyAccessibilityEvent(ui::AX_EVENT_FOCUS, GetRoot());
   BrowserAccessibilityManager::OnWindowFocused();
 }
 
 void BrowserAccessibilityManagerWin::NotifyAccessibilityEvent(
     ui::AXEvent event_type,
     BrowserAccessibility* node) {
   if (!delegate_ || !delegate_->AccessibilityGetAcceleratedWidget())
     return;
 
+  // Don't fire events when this document is stale and the user has
+  // started navigating to a new document.
+  if (user_is_navigating_away_)
+    return;
+
   // Inline text boxes are an internal implementation detail, we don't
   // expose them to Windows.
   if (node->GetRole() == ui::AX_ROLE_INLINE_TEXT_BOX)
     return;
 
   // Don't fire focus, blur, or load complete notifications if the
   // window isn't focused, because that can confuse screen readers into
   // entering their "browse" mode.
   if ((event_type == ui::AX_EVENT_FOCUS ||
        event_type == ui::AX_EVENT_BLUR ||
@@ skipping 137 matching lines @@
       unique_id_to_ax_id_map_.find(unique_id_win);
   if (iter != unique_id_to_ax_id_map_.end()) {
     BrowserAccessibility* result = GetFromID(iter->second);
     if (result)
       return result->ToBrowserAccessibilityWin();
   }
   return NULL;
 }
 
 }  // namespace content