Plumb ViewportMetrics change notifications around the world and back.

mojo/services/view_manager/public/cpp/lib/view_manager_client_impl.cc

Index: mojo/services/view_manager/public/cpp/lib/view_manager_client_impl.cc
diff --git a/mojo/services/view_manager/public/cpp/lib/view_manager_client_impl.cc b/mojo/services/view_manager/public/cpp/lib/view_manager_client_impl.cc
index 78daeb3244d4a6b6b953b5fd2ee44893195fbf04..4e2642363017daa02c4dcdd41d1aa4389c1e94fd 100644
--- a/mojo/services/view_manager/public/cpp/lib/view_manager_client_impl.cc
+++ b/mojo/services/view_manager/public/cpp/lib/view_manager_client_impl.cc
@@ -36,7 +36,8 @@ View* AddViewToViewManager(ViewManagerClientImpl* client,
   private_view.set_id(view_data->view_id);
   private_view.set_visible(view_data->visible);
   private_view.set_drawn(view_data->drawn);
-  private_view.set_viewport_metrics(view_data->viewport_metrics.Pass());
+  private_view.LocalSetViewportMetrics(ViewportMetrics(),
+                                       *view_data->viewport_metrics);
   private_view.set_properties(
       view_data->properties.To<std::map<std::string, std::vector<uint8_t>>>());
   client->AddView(view);
@@ -296,6 +297,14 @@ void ViewManagerClientImpl::OnViewBoundsChanged(Id view_id,
   ViewPrivate(view).LocalSetBounds(*old_bounds, *new_bounds);
 }
 
+void ViewManagerClientImpl::OnViewViewportMetricsChanged(
+    Id view_id,
+    ViewportMetricsPtr old_metrics,
+    ViewportMetricsPtr new_metrics) {
+  View* view = GetViewById(view_id);

[sky, 2015/01/27 23:40:23]

It's possible view isn't around anymore. Only invoke LocalSetViewportMetrics if
view is valid.

Also, because we're only sending this for the root you need to apply it to all
views.

+  ViewPrivate(view).LocalSetViewportMetrics(*old_metrics, *new_metrics);
+}
+
 void ViewManagerClientImpl::OnViewHierarchyChanged(
     Id view_id,
     Id new_parent_id,