Create ash media delegate earlier during ash shell initialization

ash/mus/bridge/wm_shell_mus.cc

 // Copyright 2016 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.
 
 #include "ash/mus/bridge/wm_shell_mus.h"
 
 #include <utility>
 
 #include "ash/common/default_accessibility_delegate.h"
 #include "ash/common/display/display_info.h"
@@ skipping 120 matching lines @@
       connector_(connector),
       session_state_delegate_(new SessionStateDelegateStub) {
   client_->AddObserver(this);
   WmShell::Set(this);
 
   CreateMaximizeModeController();
 
   CreateMruWindowTracker();
 
   accessibility_delegate_.reset(new AccessibilityDelegateMus(connector_));
-  SetMediaDelegate(base::WrapUnique(delegate()->CreateMediaDelegate()));
   SetSystemTrayDelegate(base::WrapUnique(new DefaultSystemTrayDelegate));
 
   // TODO(jamescook): Port ash::sysui::KeyboardUIMus and use it here.
   SetKeyboardUI(KeyboardUI::Create());
 }
 
 WmShellMus::~WmShellMus() {
   // This order mirrors that of Shell.
 
   // Destroy maximize mode controller early on since it has some observers which
@@ skipping 216 matching lines @@
                     OnWindowActivated(gained_active, lost_active));
 }
 
 void WmShellMus::OnDidDestroyClient(::ui::WindowTreeClient* client) {
   DCHECK_EQ(client, client_);
   RemoveClientObserver();
 }
 
 }  // namespace mus
 }  // namespace ash