A11y: Introduce High Contrast Mode and Screen Magnifier to ubar tray.

ash/system/tray/system_tray_delegate.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 ASH_SYSTEM_TRAY_SYSTEM_TRAY_DELEGATE_H_
 #define ASH_SYSTEM_TRAY_SYSTEM_TRAY_DELEGATE_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 131 matching lines @@
 
   // Shows settings related to multiple displays.
   virtual void ShowDisplaySettings() = 0;
 
   // Shows settings related to Google Drive.
   virtual void ShowDriveSettings() = 0;
 
   // Shows settings related to input methods.
   virtual void ShowIMESettings() = 0;
 
+  // Show accessilibity help.
+  virtual void ShowAccessibilityHelp() = 0;
+
   // Shows help.
   virtual void ShowHelp() = 0;
 
   // Attempts to shut down the system.
   virtual void ShutDown() = 0;
 
   // Attempts to sign out the user.
   virtual void SignOut() = 0;
 
   // Attempts to lock the screen.
@@ skipping 127 matching lines @@
   virtual void SetVolumeControlDelegate(
       scoped_ptr<VolumeControlDelegate> delegate) = 0;
 
   // Creates a dummy delegate for testing.
   static SystemTrayDelegate* CreateDummyDelegate();
 };
 
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_TRAY_SYSTEM_TRAY_DELEGATE_H_