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

ash/common/wm_shell.cc

Index: ash/common/wm_shell.cc
diff --git a/ash/common/wm_shell.cc b/ash/common/wm_shell.cc
index 2190f74ec7cbe33b43132d276fce59e20e1d445c..3e3e2db34100e932cd7f7e81b110807dfbf55e62 100644
--- a/ash/common/wm_shell.cc
+++ b/ash/common/wm_shell.cc
@@ -14,6 +14,7 @@
 #include "ash/common/devtools/ash_devtools_dom_agent.h"
 #include "ash/common/focus_cycler.h"
 #include "ash/common/keyboard/keyboard_ui.h"
+#include "ash/common/media_controller.h"
 #include "ash/common/new_window_controller.h"
 #include "ash/common/palette_delegate.h"
 #include "ash/common/session/session_controller.h"
@@ -79,7 +80,6 @@ void WmShell::Initialize(const scoped_refptr<base::SequencedWorkerPool>& pool) {
   // Some delegates access WmShell during their construction. Create them here
   // instead of the WmShell constructor.
   accessibility_delegate_.reset(delegate_->CreateAccessibilityDelegate());
-  media_delegate_.reset(delegate_->CreateMediaDelegate());
   palette_delegate_ = delegate_->CreatePaletteDelegate();
   toast_manager_.reset(new ToastManager);
 
@@ -254,6 +254,7 @@ WmShell::WmShell(std::unique_ptr<ShellDelegate> shell_delegate)
       immersive_context_(base::MakeUnique<ImmersiveContextAsh>()),
       locale_notification_controller_(
           base::MakeUnique<LocaleNotificationController>()),
+      media_controller_(base::MakeUnique<MediaController>()),
       new_window_controller_(base::MakeUnique<NewWindowController>()),
       session_controller_(base::MakeUnique<SessionController>()),
       shelf_controller_(base::MakeUnique<ShelfController>()),