Plumb ViewportMetrics change notifications around the world and back.

services/view_manager/view_manager_service_impl.cc

Index: services/view_manager/view_manager_service_impl.cc
diff --git a/services/view_manager/view_manager_service_impl.cc b/services/view_manager/view_manager_service_impl.cc
index 2ed0193e8e9d5348a044fb14e62aa94bd2bced24..e2f1bee6a642eea457a91b2a34a63538f576e20c 100644
--- a/services/view_manager/view_manager_service_impl.cc
+++ b/services/view_manager/view_manager_service_impl.cc
@@ -175,6 +175,17 @@ void ViewManagerServiceImpl::ProcessViewBoundsChanged(
                                 Rect::From(new_bounds));
 }
 
+void ViewManagerServiceImpl::ProcessViewportMetricsChanged(
+    const ServerView* view,
+    const mojo::ViewportMetrics& old_metrics,
+    const mojo::ViewportMetrics& new_metrics,
+    bool originated_change) {
+  if (!root())
+    return;
+  client()->OnViewViewportMetricsChanged(
+      ViewIdToTransportId(*root()), old_metrics.Clone(), new_metrics.Clone());
+}
+
 void ViewManagerServiceImpl::ProcessWillChangeViewHierarchy(
     const ServerView* view,
     const ServerView* new_parent,