mash: Change the MediaDelegate to a Media{Controller,Client}.

ash/common/shell_delegate.h

Index: ash/common/shell_delegate.h
diff --git a/ash/common/shell_delegate.h b/ash/common/shell_delegate.h
index d95f49acfeaf28ef1d65b3db5558ec4f3f24b363..c0070862436e66c84f2f0f2ce7ad4310ee4d3403 100644
--- a/ash/common/shell_delegate.h
+++ b/ash/common/shell_delegate.h
@@ -38,7 +38,6 @@ namespace ash {
 
 class AccessibilityDelegate;
 class GPUSupport;
-class MediaDelegate;
 class PaletteDelegate;
 class SessionStateDelegate;
 class ShelfDelegate;
@@ -113,9 +112,6 @@ class ASH_EXPORT ShellDelegate {
   // Creates a accessibility delegate. Shell takes ownership of the delegate.
   virtual AccessibilityDelegate* CreateAccessibilityDelegate() = 0;
 
-  // Creates a media delegate. Shell takes ownership of the delegate.
-  virtual MediaDelegate* CreateMediaDelegate() = 0;
-
   virtual std::unique_ptr<PaletteDelegate> CreatePaletteDelegate() = 0;
 
   // Creates a menu model for the |wm_shelf| and optional shelf |item|.