Pass shelf instances, not root windows, for ash context menus.

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 207 matching lines @@
 
 ash::NewWindowDelegate* ShellDelegateImpl::CreateNewWindowDelegate() {
   return new NewWindowDelegateImpl;
 }
 
 ash::MediaDelegate* ShellDelegateImpl::CreateMediaDelegate() {
   return new MediaDelegateImpl;
 }
 
 ui::MenuModel* ShellDelegateImpl::CreateContextMenu(
-    aura::Window* root_window,
+    ash::Shelf* shelf,
     const ash::ShelfItem* item) {
-  return new ContextMenu(root_window);
+  return new ContextMenu(shelf);
 }
 
 GPUSupport* ShellDelegateImpl::CreateGPUSupport() {
   // Real GPU support depends on src/content, so just use a stub.
   return new GPUSupportStub;
 }
 
 base::string16 ShellDelegateImpl::GetProductName() const {
   return base::string16();
 }
 
 gfx::Image ShellDelegateImpl::GetDeprecatedAcceleratorImage() const {
   return gfx::Image();
 }
 
 }  // namespace shell
 }  // namespace ash