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..3a76bb0c1a5b95f50f98a3d77060c0e7e6aa939a 100644
--- a/services/view_manager/view_manager_service_impl.cc
+++ b/services/view_manager/view_manager_service_impl.cc
@@ -175,6 +175,18 @@ 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 (originated_change || !IsViewKnown(view))

[sky, 2015/01/27 16:35:08]

This is only going to notify clients that know of |view|. As metrics are
inherited you need to notify everyone. I would notify each connection using the
connections root (don't notify if the connection doesn't have a root), eg:

if (!root())
  return;

client()->OnViewViewportMetricsChanged(ViewIdToTransportId(*root());

And be sure and clarify in the mojom docs the client is only notified for it's
root.

[eseidel, 2015/01/27 18:50:04]

I just copied this from ProcessBoundsChanged. :/

+    return;
+  client()->OnViewViewportMetricsChanged(ViewIdToTransportId(view->id()),
+                                         old_metrics.Clone(),
+                                         new_metrics.Clone());
+}
+
 void ViewManagerServiceImpl::ProcessWillChangeViewHierarchy(
     const ServerView* view,
     const ServerView* new_parent,