Plumb ViewportMetrics change notifications around the world and back.

services/view_manager/connection_manager.cc

Index: services/view_manager/connection_manager.cc
diff --git a/services/view_manager/connection_manager.cc b/services/view_manager/connection_manager.cc
index f5e408d794bb85d6b7d736d0174143b3596c7f85..5c2097dd1ffecd0eaca7b3b8965ee7cb40cb19f5 100644
--- a/services/view_manager/connection_manager.cc
+++ b/services/view_manager/connection_manager.cc
@@ -245,6 +245,15 @@ void ConnectionManager::ProcessViewBoundsChanged(const ServerView* view,
   }
 }
 
+void ConnectionManager::ProcessViewportMetricsChanged(
+    const mojo::ViewportMetrics& old_metrics,
+    const mojo::ViewportMetrics& new_metrics) {
+  for (auto& pair : connection_map_) {
+    pair.second->service()->ProcessViewportMetricsChanged(
+        old_metrics, new_metrics, IsChangeSource(pair.first));
+  }
+}
+
 void ConnectionManager::ProcessWillChangeViewHierarchy(
     const ServerView* view,
     const ServerView* new_parent,