Plumb ViewportMetrics change notifications around the world and back.

services/view_manager/view_manager_service_apptest.cc

Index: services/view_manager/view_manager_service_apptest.cc
diff --git a/services/view_manager/view_manager_service_apptest.cc b/services/view_manager/view_manager_service_apptest.cc
index 3adc80ce8d91ecdc03713e85a581e544f9578007..8e61b7604b8c4413173ef7f6311acdd9c72d8569 100644
--- a/services/view_manager/view_manager_service_apptest.cc
+++ b/services/view_manager/view_manager_service_apptest.cc
@@ -34,6 +34,7 @@ using mojo::String;
 using mojo::ViewDataPtr;
 using mojo::ViewManagerClient;
 using mojo::ViewManagerService;
+using mojo::ViewportMetricsPtr;
 
 namespace view_manager {
 
@@ -281,6 +282,12 @@ class ViewManagerClientImpl : public mojo::InterfaceImpl<ViewManagerClient>,
     tracker()->OnViewBoundsChanged(view_id, old_bounds.Pass(),
                                    new_bounds.Pass());
   }
+  void OnViewViewportMetricsChanged(Id view_id,
+                                    ViewportMetricsPtr old_metrics,
+                                    ViewportMetricsPtr new_metrics) override {
+    tracker()->OnViewViewportMetricsChanged(view_id, old_metrics.Pass(),
+                                            new_metrics.Pass());
+  }
   void OnViewHierarchyChanged(Id view,
                               Id new_parent,
                               Id old_parent,