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

components/bitmap_uploader/bitmap_uploader.h

Index: components/bitmap_uploader/bitmap_uploader.h
diff --git a/components/bitmap_uploader/bitmap_uploader.h b/components/bitmap_uploader/bitmap_uploader.h
index ce6e348c8b3dab6773c8b92112c0522a1ed640fc..cee37d619e284a7b1689c0ddcf82e642565de703 100644
--- a/components/bitmap_uploader/bitmap_uploader.h
+++ b/components/bitmap_uploader/bitmap_uploader.h
@@ -19,12 +19,8 @@
 #include "mojo/public/c/gles2/gles2.h"
 
 namespace mojo {
-namespace shell {
-namespace mojom {
 class Shell;
 }
-}
-}
 
 namespace bitmap_uploader {
 
@@ -38,7 +34,7 @@ class BITMAP_UPLOADER_EXPORT BitmapUploader
   explicit BitmapUploader(mus::Window* window);
   ~BitmapUploader() override;
 
-  void Init(mojo::shell::mojom::Shell* shell);
+  void Init(mojo::Shell* shell);
 
   // Sets the color which is RGBA.
   void SetColor(uint32_t color);