Implement hit tests/client area.

ui/views/mus/mus_client.cc

Index: ui/views/mus/mus_client.cc
diff --git a/ui/views/mus/mus_client.cc b/ui/views/mus/mus_client.cc
index cfa3f0014b502683763407262b0dfbd5d8fe2573..4baf674a5b90477469b9ccf36be77d5bd488bc12 100644
--- a/ui/views/mus/mus_client.cc
+++ b/ui/views/mus/mus_client.cc
@@ -115,6 +115,14 @@ NativeWidget* MusClient::CreateNativeWidget(
   return native_widget;
 }
 
+void MusClient::AddObserver(MusClientObserver* observer) {
+  observer_list_.AddObserver(observer);
+}
+
+void MusClient::RemoveObserver(MusClientObserver* observer) {
+  observer_list_.RemoveObserver(observer);
+}
+
 MusClient::MusClient(service_manager::Connector* connector,
                      const service_manager::Identity& identity,
                      scoped_refptr<base::SingleThreadTaskRunner> io_task_runner)
@@ -171,8 +179,8 @@ void MusClient::OnPointerEventObserved(const ui::PointerEvent& event,
 }
 
 void MusClient::OnWindowManagerFrameValuesChanged() {
-  // TODO: wire up client area. http://crbug.com/663525.
-  NOTIMPLEMENTED();
+  for (auto& observer : observer_list_)
+    observer.OnWindowManagerFrameValuesChanged();
 }
 
 aura::client::CaptureClient* MusClient::GetCaptureClient() {