Introduce ViewRoot to forward input/view events to native

content/browser/web_contents/web_contents_view_android.h

Index: content/browser/web_contents/web_contents_view_android.h
diff --git a/content/browser/web_contents/web_contents_view_android.h b/content/browser/web_contents/web_contents_view_android.h
index f2ddca62dcc9aacb7917f3e0a30225a93ed1612e..6d3b94adf4a68d034cf06f9129e45a70c96ea432 100644
--- a/content/browser/web_contents/web_contents_view_android.h
+++ b/content/browser/web_contents/web_contents_view_android.h
@@ -35,6 +35,8 @@ class WebContentsViewAndroid : public WebContentsView,
   // by the UI frontend.
   void SetContentViewCore(ContentViewCoreImpl* content_view_core);
 
+  void OnPhysicalBackingSizeChanged(int width, int height);
+
   void set_synchronous_compositor_client(SynchronousCompositorClient* client) {
     synchronous_compositor_client_ = client;
   }