Gets mash to use WmToplevelWindowEventHandler

mash/wm/bridge/wm_root_window_controller_mus.cc

 // Copyright 2016 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 "mash/wm/bridge/wm_root_window_controller_mus.h"
 
 #include "ash/wm/common/wm_root_window_controller_observer.h"
 #include "components/mus/public/cpp/window.h"
 #include "components/mus/public/cpp/window_property.h"
 #include "components/mus/public/cpp/window_tree_connection.h"
@@ skipping 93 matching lines @@
 
 void WmRootWindowControllerMus::ConfigureWidgetInitParamsForContainer(
     views::Widget* widget,
     int shell_container_id,
     views::Widget::InitParams* init_params) {
   init_params->parent_mus =
       root_window_controller_->root()->GetChildByLocalId(shell_container_id);
   DCHECK(init_params->parent_mus);
   mus::Window* new_window =
       root_window_controller_->root()->connection()->NewWindow();
+  WmWindowMus::Get(new_window)->set_widget(widget);
   init_params->native_widget = new views::NativeWidgetMus(
       widget, root_window_controller_->GetConnector(), new_window,
       mus::mojom::SurfaceType::DEFAULT);
 }
 
 ash::wm::WmWindow* WmRootWindowControllerMus::FindEventTarget(
     const gfx::Point& location_in_screen) {
   NOTIMPLEMENTED();
   return nullptr;
 }
 
 void WmRootWindowControllerMus::AddObserver(
     ash::wm::WmRootWindowControllerObserver* observer) {
   observers_.AddObserver(observer);
 }
 
 void WmRootWindowControllerMus::RemoveObserver(
     ash::wm::WmRootWindowControllerObserver* observer) {
   observers_.RemoveObserver(observer);
 }
 
 }  // namespace wm
 }  // namespace mash