Delete "shutdown without closing browsers" path

ash/shell/shell_delegate_impl.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/shell_delegate_impl.h"
 
 #include "ash/accessibility_delegate.h"
 #include "ash/default_accessibility_delegate.h"
 #include "ash/default_user_wallpaper_delegate.h"
 #include "ash/gpu_support_stub.h"
@@ skipping 83 matching lines @@
   return false;
 }
 
 bool ShellDelegateImpl::IsRunningInForcedAppMode() const {
   return false;
 }
 
 void ShellDelegateImpl::PreInit() {
 }
 
-void ShellDelegateImpl::Shutdown() {
+void ShellDelegateImpl::PreShutdown() {
 }
 
 void ShellDelegateImpl::Exit() {
   base::MessageLoopForUI::current()->Quit();
 }
 
 keyboard::KeyboardControllerProxy*
     ShellDelegateImpl::CreateKeyboardControllerProxy() {
   return new KeyboardControllerProxyStub();
 }
@@ skipping 50 matching lines @@
   // Real GPU support depends on src/content, so just use a stub.
   return new GPUSupportStub;
 }
 
 base::string16 ShellDelegateImpl::GetProductName() const {
   return base::string16();
 }
 
 }  // namespace shell
 }  // namespace ash