Ash: Support "Next Song", "Previous Song", "Play/Pause" Multi Media buttons

ash/shell_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_SHELL_DELEGATE_H_
 #define ASH_SHELL_DELEGATE_H_
 
 #include <vector>
 
 #include "ash/ash_export.h"
@@ skipping 119 matching lines @@
   virtual UserWallpaperDelegate* CreateUserWallpaperDelegate() = 0;
 
   // Creates a user action client. Shell takes ownership of the object.
   virtual aura::client::UserActionClient* CreateUserActionClient() = 0;
 
   // Opens the feedback page for "Report Issue".
   virtual void OpenFeedbackPage() = 0;
 
   // Records that the user performed an action.
   virtual void RecordUserMetricsAction(UserMetricsAction action) = 0;
+
+  // Handles the Next Track Media shortcut key.
+  virtual void HandleMediaNextTrack() = 0;
+
+  // Handles the Play/Pause Toggle Media shortcut key.
+  virtual void HandleMediaPlayPause() = 0;
+
+  // Handles the Previous Track Media shortcut key.
+  virtual void HandleMediaPrevTrack() = 0;
 };
 
 }  // namespace ash
 
 #endif  // ASH_SHELL_DELEGATE_H_