Plumb ViewportMetrics change notifications around the world and back.

services/view_manager/view_manager_service_impl.h

Index: services/view_manager/view_manager_service_impl.h
diff --git a/services/view_manager/view_manager_service_impl.h b/services/view_manager/view_manager_service_impl.h
index 2d91436a3935d23bf303308900a535441588ddfd..6fb81cdf9c2a818ab887840fd0758dc795e028dc 100644
--- a/services/view_manager/view_manager_service_impl.h
+++ b/services/view_manager/view_manager_service_impl.h
@@ -91,6 +91,10 @@ class ViewManagerServiceImpl : public mojo::ViewManagerService,
                                 const gfx::Rect& old_bounds,
                                 const gfx::Rect& new_bounds,
                                 bool originated_change);
+  void ProcessViewportMetricsChanged(const ServerView* view,
+                                     const mojo::ViewportMetrics& old_metrics,
+                                     const mojo::ViewportMetrics& new_metrics,
+                                     bool originated_change);
   void ProcessWillChangeViewHierarchy(const ServerView* view,
                                       const ServerView* new_parent,
                                       const ServerView* old_parent,