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..bba368886ea2d640cafc7696382d14decfa1cc04 100644
--- a/services/view_manager/connection_manager.cc
+++ b/services/view_manager/connection_manager.cc
@@ -245,6 +245,16 @@ void ConnectionManager::ProcessViewBoundsChanged(const ServerView* view,
   }
 }
 
+void ConnectionManager::ProcessViewportMetricsChanged(
+    const ServerView* view,
+    const mojo::ViewportMetrics& old_metrics,
+    const mojo::ViewportMetrics& new_metrics) {
+  for (auto& pair : connection_map_) {
+    pair.second->service()->ProcessViewportMetricsChanged(
+        view, old_metrics, new_metrics, IsChangeSource(pair.first));
+  }
+}
+
 void ConnectionManager::ProcessWillChangeViewHierarchy(
     const ServerView* view,
     const ServerView* new_parent,