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

ui/views/mus/aura_init.h

Index: ui/views/mus/aura_init.h
diff --git a/ui/views/mus/aura_init.h b/ui/views/mus/aura_init.h
index bff01716a2fb155cea2f86f637955ede8752b3b2..b2cf75098abc04190c63483851ba4d6ea27cd1b7 100644
--- a/ui/views/mus/aura_init.h
+++ b/ui/views/mus/aura_init.h
@@ -18,7 +18,7 @@ class FontLoader;
 }
 
 namespace mojo {
-class ApplicationImpl;
+class Shell;
 }
 
 namespace views {
@@ -28,11 +28,11 @@ class ViewsDelegate;
 // |resource_file| is the path to the apk file containing the resources.
 class VIEWS_MUS_EXPORT AuraInit {
  public:
-  AuraInit(mojo::ApplicationImpl* app, const std::string& resource_file);
+  AuraInit(mojo::Shell* shell, const std::string& resource_file);
   ~AuraInit();
 
  private:
-  void InitializeResources(mojo::ApplicationImpl* app);
+  void InitializeResources(mojo::Shell* shell);
 
 #if defined(OS_LINUX) && !defined(OS_ANDROID)
   skia::RefPtr<font_service::FontLoader> font_loader_;