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 53607b72383abac3cc3e608e192a6cb70adf3311..060fcb2dda5ea3883afb9e8bd33c386725cb1ef7 100644
--- a/ui/views/mus/mus_client.cc
+++ b/ui/views/mus/mus_client.cc
@@ -78,6 +78,14 @@ 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)
@@ -135,7 +143,8 @@ 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() {