Create ash media delegate earlier during ash shell initialization

ash/common/wm_shell.h

Index: ash/common/wm_shell.h
diff --git a/ash/common/wm_shell.h b/ash/common/wm_shell.h
index 293cc4a23bdb61dc1b7bc28cbe5ce65c11d070b9..6ae0ee1a491ae9acccb10b9578c7fb204208757d 100644
--- a/ash/common/wm_shell.h
+++ b/ash/common/wm_shell.h
@@ -59,6 +59,8 @@ class ASH_EXPORT WmShell {
   static WmShell* Get();
   static bool HasInstance() { return instance_ != nullptr; }
 
+  void Initialize();
+
   ShellDelegate* delegate() { return delegate_.get(); }
 
   BrightnessControlDelegate* brightness_control_delegate() {
@@ -229,7 +231,6 @@ class ASH_EXPORT WmShell {
 
   // Helpers to set (and initialize) or destroy various delegates.
   // TODO(msw|jamescook): Remove these once ShellDelegate, etc. are ported.
-  void SetMediaDelegate(std::unique_ptr<MediaDelegate> delegate);
   void SetSystemTrayDelegate(std::unique_ptr<SystemTrayDelegate> delegate);
   void DeleteSystemTrayDelegate();