mash: Make the power button shut the system down.

ash/shell.cc

 // Copyright (c) 2012 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 "ash/shell.h"
 
 #include <algorithm>
 #include <string>
 #include <utility>
 
@@ skipping 661 matching lines @@
 
   wm_shell_->CreatePrimaryHost();
   wm_shell_->set_root_window_for_new_windows(
       WmWindow::Get(GetPrimaryRootWindow()));
 
   if (!is_mash) {
     resolution_notification_controller_.reset(
         new ResolutionNotificationController);
   }
 
-  if (cursor_manager_)
+  if (cursor_manager_) {
     cursor_manager_->SetDisplay(
         display::Screen::GetScreen()->GetPrimaryDisplay());
+  }
 
   if (!is_mash) {
     // TODO(sky): move this to WmShell. http://crbug.com/671246.
     accelerator_controller_delegate_.reset(
         new AcceleratorControllerDelegateAura);
     wm_shell_->SetAcceleratorController(base::MakeUnique<AcceleratorController>(
         accelerator_controller_delegate_.get(), nullptr));
   }
   wm_shell_->CreateMaximizeModeController();
 
@@ skipping 241 matching lines @@
 std::unique_ptr<ui::EventTargetIterator> Shell::GetChildIterator() const {
   return std::unique_ptr<ui::EventTargetIterator>();
 }
 
 ui::EventTargeter* Shell::GetEventTargeter() {
   NOTREACHED();
   return nullptr;
 }
 
 }  // namespace ash