V2 app support step2 : Use NativeAppWindow for Activity's window.

athena/content/app_activity_proxy.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "athena/content/app_activity_proxy.h"
 
 #include "athena/content/app_activity_registry.h"
 #include "athena/wm/public/window_list_provider.h"
 #include "athena/wm/public/window_manager.h"
 #include "ui/aura/window.h"
@@ skipping 66 matching lines @@
 }
 
 bool AppActivityProxy::UsesFrame() const {
   return true;
 }
 
 views::View* AppActivityProxy::GetContentsView() {
   return view_;
 }
 
+views::Widget* AppActivityProxy::CreateWidget() {
+  return NULL;
+}
+
 void AppActivityProxy::CreateOverviewModeImage() {
   // Nothing we can do here.
 }
 
 gfx::ImageSkia AppActivityProxy::GetOverviewModeImage() {
   return image_;
 }
 
 void AppActivityProxy::PrepareContentsForOverview() {
 }
 
 void AppActivityProxy::ResetContentsView() {
 }
 
 }  // namespace athena