Plumb ViewportMetrics change notifications around the world and back.

services/view_manager/server_view.h

Index: services/view_manager/server_view.h
diff --git a/services/view_manager/server_view.h b/services/view_manager/server_view.h
index 03842e7bb5cfc0a3db9231bf362fd22fafb14f9a..bb81cc6f3e420266d8416de02c29470585ccbd7d 100644
--- a/services/view_manager/server_view.h
+++ b/services/view_manager/server_view.h
@@ -40,6 +40,9 @@ class ServerView {
   const gfx::Rect& bounds() const { return bounds_; }
   void SetBounds(const gfx::Rect& bounds);
 
+  const mojo::ViewportMetrics& viewport_metrics() { return *viewport_metrics_; }

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

Since we currently only support metrics on the root you shouldn't need to add
anything on ServerView. At some point we may want to support metrics on certain
nodes, but lets wait until we actually need that.

+  void SetViewportMetrics(const mojo::ViewportMetrics& metrics);
+
   const ServerView* parent() const { return parent_; }
   ServerView* parent() { return parent_; }
 
@@ -95,6 +98,7 @@ class ServerView {
   Views children_;
   bool visible_;
   gfx::Rect bounds_;
+  mojo::ViewportMetricsPtr viewport_metrics_;
   cc::SurfaceId surface_id_;
   float opacity_;
   gfx::Transform transform_;