Suppress accessibility events when user is navigating away.

content/browser/accessibility/browser_accessibility_manager.h

 // 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.
 
 #ifndef CONTENT_BROWSER_ACCESSIBILITY_BROWSER_ACCESSIBILITY_MANAGER_H_
 #define CONTENT_BROWSER_ACCESSIBILITY_BROWSER_ACCESSIBILITY_MANAGER_H_
 
 #include <vector>
 
 #include "base/containers/hash_tables.h"
@@ skipping 128 matching lines @@
   BrowserAccessibility* GetFromID(int32 id);
 
   // Called to notify the accessibility manager that its associated native
   // view got focused.
   virtual void OnWindowFocused();
 
   // Called to notify the accessibility manager that its associated native
   // view lost focus.
   virtual void OnWindowBlurred();
 
+  // Notify the accessibility manager about page navigation.
+  void UserIsNavigatingAway();
+  virtual void UserIsReloading();
+  void NavigationSucceeded();
+  void NavigationFailed();
+
   // Called to notify the accessibility manager that a mouse down event
   // occurred in the tab.
   void GotMouseDown();
 
   // Update the focused node to |node|, which may be null.
   // If |notify| is true, send a message to the renderer to set focus
   // to this node.
   void SetFocus(ui::AXNode* node, bool notify);
   void SetFocus(BrowserAccessibility* node, bool notify);
 
@@ skipping 138 matching lines @@
 
   // The underlying tree of accessibility objects.
   scoped_ptr<ui::AXSerializableTree> tree_;
 
   // The node that currently has focus.
   ui::AXNode* focus_;
 
   // A mapping from a node id to its wrapper of type BrowserAccessibility.
   base::hash_map<int32, BrowserAccessibility*> id_wrapper_map_;
 
+  // True if the user has initiated a navigation to another page.
+  bool user_is_navigating_away_;
+
   // The on-screen keyboard state.
   OnScreenKeyboardState osk_state_;
 
   BrowserAccessibilityFindInPageInfo find_in_page_info_;
 
   DISALLOW_COPY_AND_ASSIGN(BrowserAccessibilityManager);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_ACCESSIBILITY_BROWSER_ACCESSIBILITY_MANAGER_H_