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

mandoline/services/updater/updater_impl.h

Index: mandoline/services/updater/updater_impl.h
diff --git a/mandoline/services/updater/updater_impl.h b/mandoline/services/updater/updater_impl.h
index e1d5d7814b637a547318faf34eebf07026452933..b7154cd0ec52840ffc8aed2efdebd8de4815552d 100644
--- a/mandoline/services/updater/updater_impl.h
+++ b/mandoline/services/updater/updater_impl.h
@@ -12,13 +12,11 @@
 
 namespace updater {
 
-class ApplicationImpl;
 class UpdaterApp;
 
 class UpdaterImpl : public Updater {
  public:
-  UpdaterImpl(mojo::ApplicationImpl* app_impl,
-              UpdaterApp* application,
+  UpdaterImpl(UpdaterApp* application,
               mojo::InterfaceRequest<Updater> request);
   ~UpdaterImpl() override;
 
@@ -28,7 +26,6 @@ class UpdaterImpl : public Updater {
 
  private:
   UpdaterApp* const application_;
-  mojo::ApplicationImpl* const app_impl_;
   mojo::StrongBinding<Updater> binding_;
 
   DISALLOW_COPY_AND_ASSIGN(UpdaterImpl);