Plumb ViewportMetrics change notifications around the world and back.

services/view_manager/connection_manager.h

Index: services/view_manager/connection_manager.h
diff --git a/services/view_manager/connection_manager.h b/services/view_manager/connection_manager.h
index ad3a70345c3e5eaf8882f9199873d99add471afc..b29bbe410b81bd0f9e846d4c74aadbf2c55b742a 100644
--- a/services/view_manager/connection_manager.h
+++ b/services/view_manager/connection_manager.h
@@ -130,6 +130,9 @@ class ConnectionManager : public ServerViewDelegate,
   void ProcessViewBoundsChanged(const ServerView* view,
                                 const gfx::Rect& old_bounds,
                                 const gfx::Rect& new_bounds);
+  void ProcessViewportMetricsChanged(const ServerView* view,
+                                     const mojo::ViewportMetrics& old_metrics,
+                                     const mojo::ViewportMetrics& new_metrics);
   void ProcessWillChangeViewHierarchy(const ServerView* view,
                                       const ServerView* new_parent,
                                       const ServerView* old_parent);
@@ -179,6 +182,10 @@ class ConnectionManager : public ServerViewDelegate,
   void OnViewBoundsChanged(const ServerView* view,
                            const gfx::Rect& old_bounds,
                            const gfx::Rect& new_bounds) override;
+  void OnViewViewportMetricsChanged(
+      const ServerView* view,
+      const mojo::ViewportMetrics& old_metrics,
+      const mojo::ViewportMetrics& new_metrics) override;
   void OnViewSurfaceIdChanged(const ServerView* view) override;
   void OnViewReordered(const ServerView* view,
                        const ServerView* relative,