Adds extension APIs of events on changing volume.

chrome/browser/extensions/extension_accessibility_api.h

 // Copyright (c) 2011 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 CHROME_BROWSER_EXTENSIONS_EXTENSION_ACCESSIBILITY_API_H_
 #define CHROME_BROWSER_EXTENSIONS_EXTENSION_ACCESSIBILITY_API_H_
 #pragma once
 
 #include <string>
 #include <vector>
@@ skipping 44 matching lines @@
                        const NotificationSource& source,
                        const NotificationDetails& details);
 
   void OnWindowOpened(const AccessibilityWindowInfo* details);
   void OnWindowClosed(const AccessibilityWindowInfo* details);
   void OnControlFocused(const AccessibilityControlInfo* details);
   void OnControlAction(const AccessibilityControlInfo* details);
   void OnTextChanged(const AccessibilityControlInfo* details);
   void OnMenuOpened(const AccessibilityMenuInfo* details);
   void OnMenuClosed(const AccessibilityMenuInfo* details);
+  void OnVolumeChanged(const AccessibilityVolumeInfo* details);
 
   void DispatchEvent(Profile* profile,
                      const char* event_name,
                      const std::string& json_args);
 
   // Used for tracking registrations to history service notifications.
   NotificationRegistrar registrar_;
 
   DictionaryValue last_focused_control_dict_;
 
@@ skipping 16 matching lines @@
 
 // API function that returns the most recent focused control.
 class GetFocusedControlFunction : public SyncExtensionFunction {
   virtual ~GetFocusedControlFunction() {}
   virtual bool RunImpl();
   DECLARE_EXTENSION_FUNCTION_NAME(
       "experimental.accessibility.getFocusedControl")
 };
 
 #endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_ACCESSIBILITY_API_H_