mash: Migrate MediaDelegate ownership and access to WmShell.

ash/common/media_delegate.h

 // Copyright 2013 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_MEDIA_DELEGATE_H_
-#define ASH_MEDIA_DELEGATE_H_
+#ifndef ASH_COMMON_MEDIA_DELEGATE_H_
+#define ASH_COMMON_MEDIA_DELEGATE_H_
 
 #include "ash/common/session/session_types.h"
 
-namespace content {
-class BrowserContext;
-}
-
 namespace ash {
 
 enum MediaCaptureState {
   MEDIA_CAPTURE_NONE = 0,
   MEDIA_CAPTURE_AUDIO = 1 << 0,
   MEDIA_CAPTURE_VIDEO = 1 << 1,
   MEDIA_CAPTURE_AUDIO_VIDEO = MEDIA_CAPTURE_AUDIO | MEDIA_CAPTURE_VIDEO,
 };
 
 // A delegate class to control media playback.
@@ skipping 10 matching lines @@
   // Handles the Previous Track Media shortcut key.
   virtual void HandleMediaPrevTrack() = 0;
 
   // Returns the current media recording state of web contents that belongs to
   // the the user @ |index|. See session_types.h for a description of UserIndex.
   virtual MediaCaptureState GetMediaCaptureState(UserIndex index) = 0;
 };
 
 }  // namespace ash
 
-#endif  // ASH_MEDIA_DELEGATE_H_
+#endif  // ASH_COMMON_MEDIA_DELEGATE_H_