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

mash/wm/root_window_controller.h

 // 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.
 
 #ifndef MASH_WM_ROOT_WINDOW_CONTROLLER_H_
 #define MASH_WM_ROOT_WINDOW_CONTROLLER_H_
 
 #include "components/mus/public/cpp/window_observer.h"
 #include "components/mus/public/cpp/window_tree_delegate.h"
 #include "components/mus/public/interfaces/window_manager_constants.mojom.h"
 #include "components/mus/public/interfaces/window_tree_host.mojom.h"
 #include "mash/wm/public/interfaces/container.mojom.h"
 #include "mojo/public/cpp/bindings/binding.h"
 
 namespace mojo {
-namespace shell {
-namespace mojom {
 class Shell;
 }
-}
-}
 
 namespace mus {
 class WindowManagerClient;
 }
 
 namespace mash {
 namespace wm {
 
 class BackgroundLayout;
 class ScreenlockLayout;
@@ skipping 13 matching lines @@
   static RootWindowController* CreateUsingWindowTreeHost(
       WindowManagerApplication* app);
   static RootWindowController* CreateFromDisplay(
       WindowManagerApplication* app,
       mus::mojom::DisplayPtr display,
       mojo::InterfaceRequest<mus::mojom::WindowTreeClient> client_request);
 
   // Deletes this.
   void Destroy();
 
-  mojo::shell::mojom::Shell* GetShell();
+  mojo::Shell* GetShell();
 
   mus::Window* root() { return root_; }
 
   int window_count() { return window_count_; }
   void IncrementWindowCount() { ++window_count_; }
 
   mus::Window* GetWindowForContainer(mojom::Container container);
   mus::Window* GetWindowById(mus::Id id);
   bool WindowIsContainer(const mus::Window* window) const;
 
@@ skipping 38 matching lines @@
 
   mus::mojom::DisplayPtr display_;
 
   DISALLOW_COPY_AND_ASSIGN(RootWindowController);
 };
 
 }  // namespace wm
 }  // namespace mash
 
 #endif  // MASH_WM_ROOT_WINDOW_CONTROLLER_H_