Extract shell methods from ApplicationImpl into a base class, and pass this to Initialize() instead.

components/mus/ws/display_manager_factory.h

 // Copyright 2015 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 COMPONENTS_MUS_WS_DISPLAY_MANAGER_FACTORY_H_
 #define COMPONENTS_MUS_WS_DISPLAY_MANAGER_FACTORY_H_
 
 #include "components/mus/gles2/gpu_state.h"
 #include "mojo/public/cpp/bindings/callback.h"
 
 namespace mojo {
-class ApplicationImpl;
+class Shell;
 }
 
 namespace mus {
 
 namespace ws {
 
 class DisplayManager;
 
 // Abstract factory for DisplayManagers. Used by tests to construct test
 // DisplayManagers.
 class DisplayManagerFactory {
  public:
   virtual DisplayManager* CreateDisplayManager(
-      mojo::ApplicationImpl* app_impl,
+      mojo::Shell* shell,
       const scoped_refptr<mus::GpuState>& gpu_state,
       const scoped_refptr<mus::SurfacesState>& surfaces_state) = 0;
 };
 
 }  // namespace ws
 
 }  // namespace mus
 
 #endif  // COMPONENTS_MUS_WS_DISPLAY_MANAGER_FACTORY_H_