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

components/web_view/pending_web_view_load.cc

Index: components/web_view/pending_web_view_load.cc
diff --git a/components/web_view/pending_web_view_load.cc b/components/web_view/pending_web_view_load.cc
index d5db3543b7bbf3a9e79ed88afe9f1c2c1dda1d04..9969324c890578fd54a9a418f8659a5c8f171fcf 100644
--- a/components/web_view/pending_web_view_load.cc
+++ b/components/web_view/pending_web_view_load.cc
@@ -24,7 +24,7 @@ void PendingWebViewLoad::Init(mojo::URLRequestPtr request) {
   navigation_start_time_ =
       base::TimeTicks::FromInternalValue(request->originating_time_ticks);
   frame_connection_.reset(new FrameConnection);
-  frame_connection_->Init(web_view_->app_, std::move(request),
+  frame_connection_->Init(web_view_->shell_, std::move(request),
                           base::Bind(&PendingWebViewLoad::OnGotContentHandlerID,
                                      base::Unretained(this)));
 }