Revert 177182 - ViewTest.ChangeNativeViewHierarchyFindRoots failure

> Finally rip the global StackingClient bandaid off.
> 
> - Removes the aura::client::SetStackingClient(StackingClient*) interface.
> - Moves the ash StackingController from a singleton owned by ash::Shell to one StackingController per RootWindow owned by the ash::RootWindowController. (Also removes a spurious delegate method, where every implementation creates the same object, including tests.)
> - Removes the global DesktopStackingClient and related interfaces.
> - Fix the ChromeViewsDelegate so that it still sets context in chromeos builds.
> - Rename content::ShellStackingClientAsh to content::MinimalAsh to reflect what it really does.
> 
> In addition, the following fix ups apply:
> 
> - Previously, WebContentsViewAura asserted that it needed a context window. Now if no context window is provided, it isn't added to an aura hierarchy. There are times when that context doesn't exist: various chromeos dialogs that directly invoke WebView and toplevel extension/app windows that are created from background pages that don't have contexts.
> 
> BUG=161882
> 
> Review URL: https://codereview.chromium.org/11829040

TBR=erg@chromium.org
Review URL: https://codereview.chromium.org/11962021

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@177190 0039d316-1c4b-4281-b951-d872f2087c98

43 files changed, 419 insertions, 178 deletions

diff --git a/ash/root_window_controller.cc b/ash/root_window_controller.cc
index 9c6580a..543a084 100644
--- a/ash/root_window_controller.cc
+++ b/ash/root_window_controller.cc
@@ -26,7 +26,6 @@
 #include "ash/wm/root_window_layout_manager.h"
 #include "ash/wm/screen_dimmer.h"
 #include "ash/wm/shelf_layout_manager.h"
-#include "ash/wm/stacking_controller.h"
 #include "ash/wm/status_area_layout_manager.h"
 #include "ash/wm/system_background_controller.h"
 #include "ash/wm/system_modal_container_layout_manager.h"
@@ -169,9 +168,6 @@ RootWindowController::RootWindowController(aura::RootWindow* root_window)
       panel_layout_manager_(NULL) {
   SetRootWindowController(root_window, this);
   screen_dimmer_.reset(new ScreenDimmer(root_window));
-
-  stacking_controller_.reset(new ash::StackingController);
-  aura::client::SetStackingClient(root_window, stacking_controller_.get());
 }
 
 RootWindowController::~RootWindowController() {
diff --git a/ash/root_window_controller.h b/ash/root_window_controller.h
index 2dae441..e5e85ef1 100644
--- a/ash/root_window_controller.h
+++ b/ash/root_window_controller.h
@@ -32,7 +32,6 @@ class RootWindowEventFilter;
 
 namespace ash {
 class Launcher;
-class StackingController;
 class SystemTray;
 class ToplevelWindowEventHandler;
 
@@ -177,8 +176,6 @@ class ASH_EXPORT RootWindowController {
   scoped_ptr<aura::RootWindow> root_window_;
   RootWindowLayoutManager* root_window_layout_;
 
-  scoped_ptr<StackingController> stacking_controller_;
-
   // Widget containing system tray.
   StatusAreaWidget* status_area_widget_;
 
diff --git a/ash/shell.cc b/ash/shell.cc
index 171c121..f1c6d99 100644
--- a/ash/shell.cc
+++ b/ash/shell.cc
@@ -56,6 +56,7 @@
 #include "ash/wm/session_state_controller.h"
 #include "ash/wm/session_state_controller_impl.h"
 #include "ash/wm/session_state_controller_impl2.h"
+#include "ash/wm/stacking_controller.h"
 #include "ash/wm/system_gesture_event_filter.h"
 #include "ash/wm/system_modal_container_event_filter.h"
 #include "ash/wm/system_modal_container_layout_manager.h"
@@ -70,6 +71,7 @@
 #include "base/command_line.h"
 #include "base/debug/leak_annotations.h"
 #include "ui/aura/client/aura_constants.h"
+#include "ui/aura/client/stacking_client.h"
 #include "ui/aura/client/user_action_client.h"
 #include "ui/aura/env.h"
 #include "ui/aura/focus_manager.h"
@@ -500,6 +502,9 @@ void Shell::Init() {
   // Create Controllers that may need root window.
   // TODO(oshima): Move as many controllers before creating
   // RootWindowController as possible.
+  stacking_client_.reset(delegate_->CreateStackingClient());
+  if (stacking_client_.get())
+    aura::client::SetStackingClient(stacking_client_.get());
   visibility_controller_.reset(new AshVisibilityController);
   drag_drop_controller_.reset(new internal::DragDropController);
   user_action_client_.reset(delegate_->CreateUserActionClient());
@@ -830,6 +835,10 @@ void Shell::DoInitialWorkspaceAnimation() {
       DoInitialAnimation();
 }
 
+aura::client::StackingClient* Shell::stacking_client() {
+  return stacking_client_.get();
+}
+
 void Shell::InitRootWindowController(
     internal::RootWindowController* controller) {
   aura::RootWindow* root_window = controller->root_window();
diff --git a/ash/shell.h b/ash/shell.h
index 8978ce3..bc86059 100644
--- a/ash/shell.h
+++ b/ash/shell.h
@@ -33,6 +33,7 @@ class Window;
 namespace client {
 class ActivationClient;
 class FocusClient;
+class StackingClient;
 class UserActionClient;
 }
 }
@@ -428,6 +429,8 @@ class ASH_EXPORT Shell
   }
 #endif  // defined(OS_CHROMEOS)
 
+ aura::client::StackingClient* stacking_client();
+
  RootWindowHostFactory* root_window_host_factory() {
    return root_window_host_factory_.get();
  }
@@ -508,6 +511,7 @@ class ASH_EXPORT Shell
 
   scoped_ptr<internal::AppListController> app_list_controller_;
 
+  scoped_ptr<aura::client::StackingClient> stacking_client_;
   scoped_ptr<internal::ActivationController> activation_controller_;
   scoped_ptr<internal::CaptureController> capture_controller_;
   scoped_ptr<internal::DragDropController> drag_drop_controller_;
diff --git a/ash/shell/shell_delegate_impl.cc b/ash/shell/shell_delegate_impl.cc
index 945fae9..681dfb5 100644
--- a/ash/shell/shell_delegate_impl.cc
+++ b/ash/shell/shell_delegate_impl.cc
@@ -11,6 +11,7 @@
 #include "ash/shell/context_menu.h"
 #include "ash/shell/toplevel_window.h"
 #include "ash/shell_window_ids.h"
+#include "ash/wm/stacking_controller.h"
 #include "ash/wm/window_util.h"
 #include "base/message_loop.h"
 #include "ui/aura/window.h"
@@ -214,6 +215,10 @@ ui::MenuModel* ShellDelegateImpl::CreateContextMenu(aura::RootWindow* root) {
   return new ContextMenu(root);
 }
 
+aura::client::StackingClient* ShellDelegateImpl::CreateStackingClient() {
+  return new StackingController;
+}
+
 RootWindowHostFactory* ShellDelegateImpl::CreateRootWindowHostFactory() {
   return RootWindowHostFactory::Create();
 }
diff --git a/ash/shell/shell_delegate_impl.h b/ash/shell/shell_delegate_impl.h
index 66f6076..e94d08a 100644
--- a/ash/shell/shell_delegate_impl.h
+++ b/ash/shell/shell_delegate_impl.h
@@ -69,6 +69,7 @@ class ShellDelegateImpl : public ash::ShellDelegate {
   virtual double GetSavedScreenMagnifierScale() OVERRIDE;
   virtual ui::MenuModel* CreateContextMenu(
       aura::RootWindow* root_window) OVERRIDE;
+  virtual aura::client::StackingClient* CreateStackingClient() OVERRIDE;
   virtual RootWindowHostFactory* CreateRootWindowHostFactory() OVERRIDE;
 
  private:
diff --git a/ash/shell_delegate.h b/ash/shell_delegate.h
index 11482d5..6a9dd08 100644
--- a/ash/shell_delegate.h
+++ b/ash/shell_delegate.h
@@ -22,6 +22,7 @@ namespace aura {
 class RootWindow;
 class Window;
 namespace client {
+class StackingClient;
 class UserActionClient;
 }
 }
@@ -218,6 +219,9 @@ class ASH_EXPORT ShellDelegate {
   // Creates a menu model of the context for the |root_window|.
   virtual ui::MenuModel* CreateContextMenu(aura::RootWindow* root_window) = 0;
 
+  // Creates the stacking client. Shell takes ownership of the object.
+  virtual aura::client::StackingClient* CreateStackingClient() = 0;
+
   // Creates a root window host factory. Shell takes ownership of the returned
   // value.
   virtual RootWindowHostFactory* CreateRootWindowHostFactory() = 0;
diff --git a/ash/test/test_shell_delegate.cc b/ash/test/test_shell_delegate.cc
index 4690156..c2fdc60 100644
--- a/ash/test/test_shell_delegate.cc
+++ b/ash/test/test_shell_delegate.cc
@@ -11,6 +11,7 @@
 #include "ash/shell.h"
 #include "ash/shell_window_ids.h"
 #include "ash/test/test_launcher_delegate.h"
+#include "ash/wm/stacking_controller.h"
 #include "ash/wm/window_util.h"
 #include "content/public/test/test_browser_context.h"
 #include "ui/aura/window.h"
@@ -203,6 +204,10 @@ double TestShellDelegate::GetSavedScreenMagnifierScale() {
   return std::numeric_limits<double>::min();
 }
 
+aura::client::StackingClient* TestShellDelegate::CreateStackingClient() {
+  return new StackingController;
+}
+
 RootWindowHostFactory* TestShellDelegate::CreateRootWindowHostFactory() {
   return RootWindowHostFactory::Create();
 }
diff --git a/ash/test/test_shell_delegate.h b/ash/test/test_shell_delegate.h
index 3b0ee76..76add5d 100644
--- a/ash/test/test_shell_delegate.h
+++ b/ash/test/test_shell_delegate.h
@@ -67,6 +67,7 @@ class TestShellDelegate : public ShellDelegate {
   virtual void SaveScreenMagnifierScale(double scale) OVERRIDE;
   virtual double GetSavedScreenMagnifierScale() OVERRIDE;
   virtual ui::MenuModel* CreateContextMenu(aura::RootWindow* root) OVERRIDE;
+  virtual aura::client::StackingClient* CreateStackingClient() OVERRIDE;
   virtual RootWindowHostFactory* CreateRootWindowHostFactory() OVERRIDE;
 
   int num_exit_requests() const { return num_exit_requests_; }
diff --git a/chrome/browser/ui/app_modal_dialogs/javascript_app_modal_dialog.cc b/chrome/browser/ui/app_modal_dialogs/javascript_app_modal_dialog.cc
index be2c7e8..261a8fc 100644
--- a/chrome/browser/ui/app_modal_dialogs/javascript_app_modal_dialog.cc
+++ b/chrome/browser/ui/app_modal_dialogs/javascript_app_modal_dialog.cc
@@ -10,10 +10,6 @@
 #include "content/public/browser/web_contents_view.h"
 #include "ui/base/text/text_elider.h"
 
-#if defined(USE_AURA)
-#include "ui/aura/root_window.h"
-#endif
-
 using content::JavaScriptDialogCreator;
 using content::WebContents;
 
@@ -84,13 +80,6 @@ JavaScriptAppModalDialog::~JavaScriptAppModalDialog() {
 NativeAppModalDialog* JavaScriptAppModalDialog::CreateNativeDialog() {
   gfx::NativeWindow parent_window =
       web_contents()->GetView()->GetTopLevelNativeWindow();
-#if defined(USE_AURA)
-  if (!parent_window->GetRootWindow()) {
-    // When we are part of a WebContents that isn't actually being displayed on
-    // the screen, we can't actually attach to it.
-    parent_window = NULL;
-  }
-#endif
   return NativeAppModalDialog::CreateNativeJavaScriptPrompt(this,
                                                             parent_window);
 }
diff --git a/chrome/browser/ui/ash/chrome_shell_delegate.cc b/chrome/browser/ui/ash/chrome_shell_delegate.cc
index a0bc043..b784036 100644
--- a/chrome/browser/ui/ash/chrome_shell_delegate.cc
+++ b/chrome/browser/ui/ash/chrome_shell_delegate.cc
@@ -8,6 +8,7 @@
 #include "ash/launcher/launcher_types.h"
 #include "ash/magnifier/magnifier_constants.h"
 #include "ash/system/tray/system_tray_delegate.h"
+#include "ash/wm/stacking_controller.h"
 #include "ash/wm/window_util.h"
 #include "base/bind.h"
 #include "base/command_line.h"
@@ -556,6 +557,10 @@ ui::MenuModel* ChromeShellDelegate::CreateContextMenu(aura::RootWindow* root) {
   return new LauncherContextMenu(launcher_delegate_, root);
 }
 
+aura::client::StackingClient* ChromeShellDelegate::CreateStackingClient() {
+  return new ash::StackingController;
+}
+
 ash::RootWindowHostFactory* ChromeShellDelegate::CreateRootWindowHostFactory() {
   return ash::RootWindowHostFactory::Create();
 }
diff --git a/chrome/browser/ui/ash/chrome_shell_delegate.h b/chrome/browser/ui/ash/chrome_shell_delegate.h
index 1cf04aa..7270a37 100644
--- a/chrome/browser/ui/ash/chrome_shell_delegate.h
+++ b/chrome/browser/ui/ash/chrome_shell_delegate.h
@@ -83,6 +83,7 @@ class ChromeShellDelegate : public ash::ShellDelegate,
   virtual void SaveScreenMagnifierScale(double scale) OVERRIDE;
   virtual double GetSavedScreenMagnifierScale() OVERRIDE;
   virtual ui::MenuModel* CreateContextMenu(aura::RootWindow* root) OVERRIDE;
+  virtual aura::client::StackingClient* CreateStackingClient() OVERRIDE;
   virtual ash::RootWindowHostFactory* CreateRootWindowHostFactory() OVERRIDE;
 
   // content::NotificationObserver override:
diff --git a/chrome/browser/ui/aura/chrome_browser_main_extra_parts_aura.cc b/chrome/browser/ui/aura/chrome_browser_main_extra_parts_aura.cc
index 88b9861..21387c8 100644
--- a/chrome/browser/ui/aura/chrome_browser_main_extra_parts_aura.cc
+++ b/chrome/browser/ui/aura/chrome_browser_main_extra_parts_aura.cc
@@ -7,9 +7,11 @@
 #include "chrome/browser/chrome_browser_main.h"
 #include "chrome/browser/toolkit_extra_parts.h"
 #include "chrome/browser/ui/aura/active_desktop_monitor.h"
+#include "chrome/browser/ui/aura/stacking_client_aura.h"
 #include "ui/aura/env.h"
 #include "ui/gfx/screen.h"
 #include "ui/views/widget/desktop_aura/desktop_screen.h"
+#include "ui/views/widget/desktop_aura/desktop_stacking_client.h"
 #include "ui/views/widget/native_widget_aura.h"
 
 #if defined(OS_LINUX)
@@ -37,6 +39,8 @@ void ChromeBrowserMainExtraPartsAura::PreProfileInit() {
   {
     gfx::Screen::SetScreenInstance(gfx::SCREEN_TYPE_NATIVE,
                                    views::CreateDesktopScreen());
+    stacking_client_.reset(new views::DesktopStackingClient);
+    aura::client::SetStackingClient(stacking_client_.get());
   }
 #endif
 
@@ -47,6 +51,7 @@ void ChromeBrowserMainExtraPartsAura::PreProfileInit() {
 }
 
 void ChromeBrowserMainExtraPartsAura::PostMainMessageLoopRun() {
+  stacking_client_.reset();
   active_desktop_monitor_.reset();
 
   // aura::Env instance is deleted in BrowserProcessImpl::StartTearDown
diff --git a/chrome/browser/ui/aura/chrome_browser_main_extra_parts_aura.h b/chrome/browser/ui/aura/chrome_browser_main_extra_parts_aura.h
index c6573c7..4bb8cfe 100644
--- a/chrome/browser/ui/aura/chrome_browser_main_extra_parts_aura.h
+++ b/chrome/browser/ui/aura/chrome_browser_main_extra_parts_aura.h
@@ -10,6 +10,12 @@
 #include "base/memory/scoped_ptr.h"
 #include "chrome/browser/chrome_browser_main_extra_parts.h"
 
+namespace aura {
+namespace client {
+class StackingClient;
+}
+}
+
 class ActiveDesktopMonitor;
 
 class ChromeBrowserMainExtraPartsAura : public ChromeBrowserMainExtraParts {
@@ -22,6 +28,7 @@ class ChromeBrowserMainExtraPartsAura : public ChromeBrowserMainExtraParts {
   virtual void PostMainMessageLoopRun() OVERRIDE;
 
  private:
+  scoped_ptr<aura::client::StackingClient> stacking_client_;
   scoped_ptr<ActiveDesktopMonitor> active_desktop_monitor_;
 
   DISALLOW_COPY_AND_ASSIGN(ChromeBrowserMainExtraPartsAura);
diff --git a/chrome/browser/ui/aura/stacking_client_aura.cc b/chrome/browser/ui/aura/stacking_client_aura.cc
new file mode 100644
index 0000000..e2e70e4
--- /dev/null
+++ b/chrome/browser/ui/aura/stacking_client_aura.cc
@@ -0,0 +1,33 @@
+// 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 "chrome/browser/ui/aura/stacking_client_aura.h"
+
+#include "ash/shell.h"
+#include "ash/wm/stacking_controller.h"
+#include "ui/aura/focus_manager.h"
+#include "ui/aura/root_window.h"
+#include "ui/aura/window.h"
+#include "ui/views/widget/desktop_aura/desktop_native_widget_aura.h"
+#include "ui/views/widget/desktop_aura/desktop_stacking_client.h"
+
+StackingClientAura::StackingClientAura() {
+  desktop_stacking_client_.reset(new views::DesktopStackingClient);
+}
+
+StackingClientAura::~StackingClientAura() {
+}
+
+aura::Window* StackingClientAura::GetDefaultParent(aura::Window* context,
+                                                   aura::Window* window,
+                                                   const gfx::Rect& bounds) {
+#if defined(USE_ASH)
+  if (chrome::GetHostDesktopTypeForNativeView(context) ==
+      chrome::HOST_DESKTOP_TYPE_ASH) {
+    return ash::Shell::GetInstance()->stacking_client()->GetDefaultParent(
+        context, window, bounds);
+  }
+#endif
+  return desktop_stacking_client_->GetDefaultParent(context, window, bounds);
+}
diff --git a/chrome/browser/ui/aura/stacking_client_aura.h b/chrome/browser/ui/aura/stacking_client_aura.h
new file mode 100644
index 0000000..e478df8
--- /dev/null
+++ b/chrome/browser/ui/aura/stacking_client_aura.h
@@ -0,0 +1,42 @@
+// 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.
+
+#ifndef CHROME_BROWSER_UI_AURA_STACKING_CLIENT_AURA_H_
+#define CHROME_BROWSER_UI_AURA_STACKING_CLIENT_AURA_H_
+
+#include "ui/aura/client/stacking_client.h"
+
+#include "base/basictypes.h"
+#include "base/compiler_specific.h"
+#include "base/memory/scoped_ptr.h"
+#include "chrome/browser/ui/host_desktop.h"
+
+namespace ash {
+class StackingController;
+}
+
+namespace views {
+class DesktopStackingClient;
+class Window;
+}
+
+// A stacking client for the two worlds aura, dispatches to either a
+// DesktopStackingClient or an ash::StackingController.
+class StackingClientAura : public aura::client::StackingClient {
+ public:
+  StackingClientAura();
+  virtual ~StackingClientAura();
+
+  // Overridden from client::StackingClient:
+  virtual aura::Window* GetDefaultParent(aura::Window* context,
+                                         aura::Window* window,
+                                         const gfx::Rect& bounds) OVERRIDE;
+
+ private:
+  scoped_ptr<views::DesktopStackingClient> desktop_stacking_client_;
+
+  DISALLOW_COPY_AND_ASSIGN(StackingClientAura);
+};
+
+#endif  // CHROME_BROWSER_UI_AURA_STACKING_CLIENT_AURA_H_
diff --git a/chrome/browser/ui/views/ash/chrome_browser_main_extra_parts_ash.cc b/chrome/browser/ui/views/ash/chrome_browser_main_extra_parts_ash.cc
index bd06618..44b9f3e3 100644
--- a/chrome/browser/ui/views/ash/chrome_browser_main_extra_parts_ash.cc
+++ b/chrome/browser/ui/views/ash/chrome_browser_main_extra_parts_ash.cc
@@ -15,6 +15,7 @@
 #include "ui/gfx/screen.h"
 #include "ui/gfx/screen_type_delegate.h"
 #include "ui/views/widget/desktop_aura/desktop_screen.h"
+#include "ui/views/widget/desktop_aura/desktop_stacking_client.h"
 
 #if defined(FILE_MANAGER_EXTENSION)
 #include "chrome/browser/ui/views/select_file_dialog_extension.h"
diff --git a/chrome/browser/ui/views/chrome_views_delegate.cc b/chrome/browser/ui/views/chrome_views_delegate.cc
index 4be7e0f..3d4448e 100644
--- a/chrome/browser/ui/views/chrome_views_delegate.cc
+++ b/chrome/browser/ui/views/chrome_views_delegate.cc
@@ -24,12 +24,9 @@
 #include "chrome/browser/app_icon_win.h"
 #endif
 
-#if defined(USE_AURA)
-#include "ui/aura/root_window.h"
-#endif
-
 #if defined(USE_AURA) && !defined(OS_CHROMEOS)
 #include "chrome/browser/ui/host_desktop.h"
+#include "ui/aura/root_window.h"
 #include "ui/views/widget/desktop_aura/desktop_native_widget_aura.h"
 #include "ui/views/widget/native_widget_aura.h"
 #endif
@@ -177,17 +174,12 @@ content::WebContents* ChromeViewsDelegate::CreateWebContents(
 void ChromeViewsDelegate::OnBeforeWidgetInit(
     views::Widget::InitParams* params,
     views::internal::NativeWidgetDelegate* delegate) {
+#if defined(USE_AURA) && !defined(OS_CHROMEOS)
   // If we already have a native_widget, we don't have to try to come
   // up with one.
   if (params->native_widget)
     return;
 
-#if defined(OS_CHROMEOS)
-  // When we are doing straight chromeos builds, we still need to handle the
-  // toplevel window case.
-  if (params->parent == NULL && params->context == NULL && params->top_level)
-    params->context = ash::Shell::GetPrimaryRootWindow();
-#elif defined(USE_AURA)
   // While the majority of the time, context wasn't plumbed through due to the
   // existence of a global StackingClient, if this window is a toplevel, it's
   // possible that there is no contextual state that we can use.
diff --git a/chrome/browser/ui/views/chrome_web_dialog_view.cc b/chrome/browser/ui/views/chrome_web_dialog_view.cc
index c73f6ea..cc0a917 100644
--- a/chrome/browser/ui/views/chrome_web_dialog_view.cc
+++ b/chrome/browser/ui/views/chrome_web_dialog_view.cc
@@ -13,21 +13,9 @@ namespace chrome {
 gfx::NativeWindow ShowWebDialog(gfx::NativeWindow parent,
                                 content::BrowserContext* context,
                                 ui::WebDialogDelegate* delegate) {
-  views::Widget* widget = NULL;
-  if (parent) {
-    widget = views::Widget::CreateWindowWithParent(
-        new views::WebDialogView(context,
-                                 delegate,
-                                 new ChromeWebContentsHandler),
-        parent);
-  } else {
-    // We shouldn't be called with a NULL parent, but sometimes are.
-    widget = views::Widget::CreateWindow(
-        new views::WebDialogView(context,
-                                 delegate,
-                                 new ChromeWebContentsHandler));
-  }
-
+  views::Widget* widget = views::Widget::CreateWindowWithParent(
+      new views::WebDialogView(context, delegate, new ChromeWebContentsHandler),
+      parent);
   widget->Show();
   return widget->GetNativeWindow();
 }
diff --git a/chrome/browser/ui/views/javascript_app_modal_dialog_views.cc b/chrome/browser/ui/views/javascript_app_modal_dialog_views.cc
index d715b05..d324d37 100644
--- a/chrome/browser/ui/views/javascript_app_modal_dialog_views.cc
+++ b/chrome/browser/ui/views/javascript_app_modal_dialog_views.cc
@@ -162,9 +162,6 @@ NativeAppModalDialog* NativeAppModalDialog::CreateNativeJavaScriptPrompt(
     JavaScriptAppModalDialog* dialog,
     gfx::NativeWindow parent_window) {
   JavaScriptAppModalDialogViews* d = new JavaScriptAppModalDialogViews(dialog);
-  if (parent_window)
-    views::Widget::CreateWindowWithParent(d, parent_window);
-  else
-    views::Widget::CreateWindow(d);
+  views::Widget::CreateWindowWithParent(d, parent_window);
   return d;
 }
diff --git a/chrome/browser/ui/views/simple_message_box_views.cc b/chrome/browser/ui/views/simple_message_box_views.cc
index 2faa66f..f87e526 100644
--- a/chrome/browser/ui/views/simple_message_box_views.cc
+++ b/chrome/browser/ui/views/simple_message_box_views.cc
@@ -167,10 +167,7 @@ MessageBoxResult ShowMessageBox(gfx::NativeWindow parent,
   scoped_refptr<SimpleMessageBoxViews> dialog(
       new SimpleMessageBoxViews(title, message, type));
 
-  if (parent)
-    views::Widget::CreateWindowWithParent(dialog, parent)->Show();
-  else
-    views::Widget::CreateWindow(dialog)->Show();
+  views::Widget::CreateWindowWithParent(dialog, parent)->Show();
 
 #if defined(USE_AURA)
   // Use the widget's window itself so that the message loop
diff --git a/chrome/chrome_browser_ui.gypi b/chrome/chrome_browser_ui.gypi
index fa14a98..378c6ea 100644
--- a/chrome/chrome_browser_ui.gypi
+++ b/chrome/chrome_browser_ui.gypi
@@ -194,6 +194,8 @@
         'browser/ui/aura/active_desktop_monitor.h',
         'browser/ui/aura/chrome_browser_main_extra_parts_aura.cc',
         'browser/ui/aura/chrome_browser_main_extra_parts_aura.h',
+        'browser/ui/aura/stacking_client_aura.cc',
+        'browser/ui/aura/stacking_client_aura.h',
         'browser/ui/aura/tabs/dock_info_aurax11.cc',
         'browser/ui/autofill/autofill_dialog_controller.cc',
         'browser/ui/autofill/autofill_dialog_controller.h',
diff --git a/content/browser/web_contents/web_contents_view_aura.cc b/content/browser/web_contents/web_contents_view_aura.cc
index 4b9e9ce..a6c8cf4 100644
--- a/content/browser/web_contents/web_contents_view_aura.cc
+++ b/content/browser/web_contents/web_contents_view_aura.cc
@@ -634,18 +634,10 @@ void WebContentsViewAura::CreateView(
   window_->SetType(aura::client::WINDOW_TYPE_CONTROL);
   window_->SetTransparent(false);
   window_->Init(ui::LAYER_NOT_DRAWN);
-  if (context) {
-    // There are places where there is no context currently because object
-    // hierarchies are built before they're attached to a Widget. (See
-    // views::WebView as an example; GetWidget() returns NULL at the point
-    // where we are created.)
-    //
-    // It should be OK to not set a default parent since such users will
-    // explicitly add this WebContentsViewAura to their tree after they create
-    // us.
-    window_->SetDefaultParentByRootWindow(context->GetRootWindow(),
-                                          gfx::Rect());
-  }
+  // TODO(mukai, erg): Should use a non-NULL value later when the DCHECK is
+  // turned on in SetDefaultParentByRootWindow().
+  aura::RootWindow* target_root = context ? context->GetRootWindow() : NULL;
+  window_->SetDefaultParentByRootWindow(target_root, gfx::Rect());
   window_->layer()->SetMasksToBounds(true);
   window_->SetName("WebContentsViewAura");
 
diff --git a/content/content_shell.gypi b/content/content_shell.gypi
index 2bb1417..429f0a9 100644
--- a/content/content_shell.gypi
+++ b/content/content_shell.gypi
@@ -54,8 +54,6 @@
       'sources': [
         'shell/geolocation/shell_access_token_store.cc',
         'shell/geolocation/shell_access_token_store.h',
-        'shell/minimal_ash.cc',
-        'shell/minimal_ash.h',
         'shell/paths_mac.h',
         'shell/paths_mac.mm',
         'shell/shell.cc',
@@ -106,6 +104,8 @@
         'shell/shell_resource_context.h',
         'shell/shell_resource_dispatcher_host_delegate.cc',
         'shell/shell_resource_dispatcher_host_delegate.h',
+        'shell/shell_stacking_client_ash.cc',
+        'shell/shell_stacking_client_ash.h',
         'shell/shell_switches.cc',
         'shell/shell_switches.h',
         'shell/shell_url_request_context_getter.cc',
diff --git a/content/shell/minimal_ash.cc b/content/shell/minimal_ash.cc
deleted file mode 100644
index e1ff94a..0000000
--- a/content/shell/minimal_ash.cc
+++ /dev/null
@@ -1,53 +0,0 @@
-// 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 "content/shell/minimal_ash.h"
-
-#include "ui/aura/client/default_capture_client.h"
-#include "ui/aura/focus_manager.h"
-#include "ui/aura/root_window.h"
-#include "ui/aura/test/test_activation_client.h"
-#include "ui/views/corewm/compound_event_filter.h"
-#include "ui/views/corewm/input_method_event_filter.h"
-
-namespace content {
-
-MinimalAsh::MinimalAsh() {
-  root_window_.reset(new aura::RootWindow(
-      aura::RootWindow::CreateParams(gfx::Rect(100, 100))));
-  root_window_->Init();
-  aura::client::SetStackingClient(root_window_.get(), this);
-
-  focus_client_.reset(new aura::FocusManager);
-  aura::client::SetFocusClient(root_window_.get(), focus_client_.get());
-
-  root_window_event_filter_ = new views::corewm::CompoundEventFilter;
-  // Pass ownership of the filter to the root_window.
-  root_window_->SetEventFilter(root_window_event_filter_);
-
-  input_method_filter_.reset(new views::corewm::InputMethodEventFilter(
-      root_window_->GetAcceleratedWidget()));
-  input_method_filter_->SetInputMethodPropertyInRootWindow(
-      root_window_.get());
-  root_window_event_filter_->AddHandler(input_method_filter_.get());
-
-  test_activation_client_.reset(
-      new aura::test::TestActivationClient(root_window_.get()));
-
-  capture_client_.reset(
-      new aura::client::DefaultCaptureClient(root_window_.get()));
-}
-
-MinimalAsh::~MinimalAsh() {
-  root_window_event_filter_->RemoveHandler(input_method_filter_.get());
-}
-
-aura::Window* MinimalAsh::GetDefaultParent(
-    aura::Window* context,
-    aura::Window* window,
-    const gfx::Rect& bounds) {
-  return root_window_.get();
-}
-
-}  // namespace content
diff --git a/content/shell/shell.h b/content/shell/shell.h
index e2162e8..82e2a6a 100644
--- a/content/shell/shell.h
+++ b/content/shell/shell.h
@@ -1,6 +1,7 @@
 // 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.
+
 #ifndef CONTENT_SHELL_SHELL_H_
 #define CONTENT_SHELL_SHELL_H_
 
@@ -26,15 +27,15 @@ typedef struct _GtkToolItem GtkToolItem;
 #elif defined(OS_ANDROID)
 #include "base/android/scoped_java_ref.h"
 #elif defined(USE_AURA)
-#if defined(OS_CHROMEOS)
-namespace content {
-class MinimalAsh;
-}
-#endif
 namespace views {
 class Widget;
 class ViewsDelegate;
 }
+namespace aura {
+namespace client {
+class StackingClient;
+}
+}
 #endif
 
 class GURL;
@@ -236,9 +237,7 @@ class Shell : public WebContentsDelegate,
 #elif defined(OS_ANDROID)
   base::android::ScopedJavaGlobalRef<jobject> java_object_;
 #elif defined(USE_AURA)
-#if defined(OS_CHROMEOS)
-  static content::MinimalAsh* minimal_ash_;
-#endif
+  static aura::client::StackingClient* stacking_client_;
   static views::ViewsDelegate* views_delegate_;
 
   views::Widget* window_widget_;
diff --git a/content/shell/shell_aura.cc b/content/shell/shell_aura.cc
index 6641cda..a0986c4 100644
--- a/content/shell/shell_aura.cc
+++ b/content/shell/shell_aura.cc
@@ -29,8 +29,10 @@
 
 #if defined(OS_CHROMEOS)
 #include "chromeos/dbus/dbus_thread_manager.h"
-#include "content/shell/minimal_ash.h"
+#include "content/shell/shell_stacking_client_ash.h"
 #include "ui/aura/test/test_screen.h"
+#else
+#include "ui/views/widget/desktop_aura/desktop_stacking_client.h"
 #endif
 
 // ViewDelegate implementation for aura content shell
@@ -272,9 +274,7 @@ using views::ShellWindowDelegateView;
 
 namespace content {
 
-#if defined(OS_CHROMEOS)
-MinimalAsh* Shell::minimal_ash_ = NULL;
-#endif
+aura::client::StackingClient* Shell::stacking_client_ = NULL;
 views::ViewsDelegate* Shell::views_delegate_ = NULL;
 
 // static
@@ -283,21 +283,21 @@ void Shell::PlatformInitialize() {
   chromeos::DBusThreadManager::Initialize();
 #endif
 #if defined(OS_CHROMEOS)
+  stacking_client_ = new content::ShellStackingClientAsh();
   gfx::Screen::SetScreenInstance(
       gfx::SCREEN_TYPE_NATIVE, new aura::TestScreen);
-  minimal_ash_ = new content::MinimalAsh();
 #else
+  stacking_client_ = new views::DesktopStackingClient();
   gfx::Screen::SetScreenInstance(
       gfx::SCREEN_TYPE_NATIVE, views::CreateDesktopScreen());
 #endif
+  aura::client::SetStackingClient(stacking_client_);
   views_delegate_ = new ShellViewsDelegateAura();
 }
 
 void Shell::PlatformExit() {
-#if defined(OS_CHROMEOS)
-  if (minimal_ash_)
-    delete minimal_ash_;
-#endif
+  if (stacking_client_)
+    delete stacking_client_;
   if (views_delegate_)
     delete views_delegate_;
 #if defined(OS_CHROMEOS)
@@ -334,18 +334,9 @@ void Shell::PlatformSetIsLoading(bool loading) {
 }
 
 void Shell::PlatformCreateWindow(int width, int height) {
-#if defined(OS_CHROMEOS)
-  window_widget_ =
-      views::Widget::CreateWindowWithContextAndBounds(
-          new ShellWindowDelegateView(this),
-          minimal_ash_->GetDefaultParent(NULL, NULL, gfx::Rect()),
-          gfx::Rect(0, 0, width, height));
-#else
   window_widget_ =
       views::Widget::CreateWindowWithBounds(new ShellWindowDelegateView(this),
                gfx::Rect(0, 0, width, height));
-#endif
-
   window_ = window_widget_->GetNativeWindow();
   window_widget_->Show();
 }
diff --git a/content/shell/shell_stacking_client_ash.cc b/content/shell/shell_stacking_client_ash.cc
new file mode 100644
index 0000000..f9e7c0a
--- /dev/null
+++ b/content/shell/shell_stacking_client_ash.cc
@@ -0,0 +1,56 @@
+// 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 "content/shell/shell_stacking_client_ash.h"
+
+#include "ui/aura/client/default_capture_client.h"
+#include "ui/aura/focus_manager.h"
+#include "ui/aura/root_window.h"
+#include "ui/aura/test/test_activation_client.h"
+#include "ui/views/corewm/compound_event_filter.h"
+#include "ui/views/corewm/input_method_event_filter.h"
+
+namespace content {
+
+ShellStackingClientAsh::ShellStackingClientAsh() {
+}
+
+ShellStackingClientAsh::~ShellStackingClientAsh() {
+  if (root_window_.get())
+    root_window_event_filter_->RemoveHandler(input_method_filter_.get());
+
+  aura::client::SetStackingClient(NULL);
+}
+
+aura::Window* ShellStackingClientAsh::GetDefaultParent(
+    aura::Window* context,
+    aura::Window* window,
+    const gfx::Rect& bounds) {
+  if (!root_window_.get()) {
+    root_window_.reset(new aura::RootWindow(
+        aura::RootWindow::CreateParams(gfx::Rect(100, 100))));
+    root_window_->Init();
+    focus_client_.reset(new aura::FocusManager);
+    aura::client::SetFocusClient(root_window_.get(), focus_client_.get());
+
+    root_window_event_filter_ = new views::corewm::CompoundEventFilter;
+    // Pass ownership of the filter to the root_window.
+    root_window_->SetEventFilter(root_window_event_filter_);
+
+    input_method_filter_.reset(new views::corewm::InputMethodEventFilter(
+                                   root_window_->GetAcceleratedWidget()));
+    input_method_filter_->SetInputMethodPropertyInRootWindow(
+        root_window_.get());
+    root_window_event_filter_->AddHandler(input_method_filter_.get());
+
+    test_activation_client_.reset(
+        new aura::test::TestActivationClient(root_window_.get()));
+
+    capture_client_.reset(
+        new aura::client::DefaultCaptureClient(root_window_.get()));
+  }
+  return root_window_.get();
+}
+
+}  // namespace content
diff --git a/content/shell/minimal_ash.h b/content/shell/shell_stacking_client_ash.h
index f3ec43b..de169c4 100644
--- a/content/shell/minimal_ash.h
+++ b/content/shell/shell_stacking_client_ash.h
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#ifndef CONTENT_SHELL_MINIMAL_ASH_H_
-#define CONTENT_SHELL_MINIMAL_ASH_H_
+#ifndef CONTENT_SHELL_SHELL_STACKING_CLIENT_ASH_H_
+#define CONTENT_SHELL_SHELL_STACKING_CLIENT_ASH_H_
 
 #include "base/compiler_specific.h"
 #include "base/memory/scoped_ptr.h"
@@ -37,10 +37,10 @@ namespace content {
 // Creates a minimal environment for running the shell. We can't pull in all of
 // ash here, but we can create attach several of the same things we'd find in
 // the ash parts of the code.
-class MinimalAsh : public aura::client::StackingClient {
+class ShellStackingClientAsh : public aura::client::StackingClient {
  public:
-  MinimalAsh();
-  virtual ~MinimalAsh();
+  ShellStackingClientAsh();
+  virtual ~ShellStackingClientAsh();
 
   // Overridden from client::StackingClient:
   virtual aura::Window* GetDefaultParent(aura::Window* context,
@@ -58,9 +58,9 @@ class MinimalAsh : public aura::client::StackingClient {
   scoped_ptr<aura::test::TestActivationClient> test_activation_client_;
   scoped_ptr<aura::client::FocusClient> focus_client_;
 
-  DISALLOW_COPY_AND_ASSIGN(MinimalAsh);
+  DISALLOW_COPY_AND_ASSIGN(ShellStackingClientAsh);
 };
 
 }  // namespace content;
 
-#endif  // CONTENT_SHELL_MINIMAL_ASH_H_
+#endif  // CONTENT_SHELL_SHELL_STACKING_CLIENT_ASH_H_
diff --git a/ui/aura/client/stacking_client.cc b/ui/aura/client/stacking_client.cc
index 5d93d98..2bab521 100644
--- a/ui/aura/client/stacking_client.cc
+++ b/ui/aura/client/stacking_client.cc
@@ -16,22 +16,34 @@ namespace client {
 DEFINE_WINDOW_PROPERTY_KEY(
     StackingClient*, kRootWindowStackingClientKey, NULL);
 
-void SetStackingClient(Window* window, StackingClient* stacking_client) {
-  DCHECK(window);
+void SetStackingClient(StackingClient* stacking_client) {
+  Env::GetInstance()->set_stacking_client(stacking_client);
+}
 
-  RootWindow* root_window = window->GetRootWindow();
-  DCHECK(root_window);
-  root_window->SetProperty(kRootWindowStackingClientKey, stacking_client);
+StackingClient* GetStackingClient() {
+  return Env::GetInstance()->stacking_client();
+}
+
+void SetStackingClient(Window* window, StackingClient* stacking_client) {
+  if (window) {
+    RootWindow* root_window = window->GetRootWindow();
+    DCHECK(root_window);
+    root_window->SetProperty(kRootWindowStackingClientKey, stacking_client);
+  } else {
+    SetStackingClient(stacking_client);
+  }
 }
 
 StackingClient* GetStackingClient(Window* window) {
-  DCHECK(window);
-  RootWindow* root_window = window->GetRootWindow();
-  DCHECK(root_window);
-  StackingClient* root_window_stacking_client =
-      root_window->GetProperty(kRootWindowStackingClientKey);
-  DCHECK(root_window_stacking_client);
-  return root_window_stacking_client;
+  if (window) {
+    RootWindow* root_window = window->GetRootWindow();
+    DCHECK(root_window);
+    StackingClient* root_window_stacking_client =
+        root_window->GetProperty(kRootWindowStackingClientKey);
+    if (root_window_stacking_client)
+      return root_window_stacking_client;
+  }
+  return GetStackingClient();
 }
 
 }  // namespace client
diff --git a/ui/aura/client/stacking_client.h b/ui/aura/client/stacking_client.h
index 89f83eb..6c0aa59 100644
--- a/ui/aura/client/stacking_client.h
+++ b/ui/aura/client/stacking_client.h
@@ -35,6 +35,10 @@ class AURA_EXPORT StackingClient {
       const gfx::Rect& bounds) = 0;
 };
 
+// Set/Get the default stacking client.
+AURA_EXPORT void SetStackingClient(StackingClient* stacking_client);
+StackingClient* GetStackingClient();
+
 // Set/Get a stacking client for a specific window. Setting the stacking client
 // sets the stacking client on the window's RootWindow, not the window itself.
 // Likewise getting obtains it from the window's RootWindow. If |window| is
diff --git a/ui/aura/demo/demo_main.cc b/ui/aura/demo/demo_main.cc
index 4d27b50..b688e45 100644
--- a/ui/aura/demo/demo_main.cc
+++ b/ui/aura/demo/demo_main.cc
@@ -81,11 +81,11 @@ class DemoStackingClient : public aura::client::StackingClient {
  public:
   explicit DemoStackingClient(aura::RootWindow* root_window)
       : root_window_(root_window) {
-    aura::client::SetStackingClient(root_window_, this);
+    aura::client::SetStackingClient(this);
   }
 
   virtual ~DemoStackingClient() {
-    aura::client::SetStackingClient(root_window_, NULL);
+    aura::client::SetStackingClient(NULL);
   }
 
   // Overridden from aura::client::StackingClient:
diff --git a/ui/aura/env.cc b/ui/aura/env.cc
index ecccaf1..bd094c0 100644
--- a/ui/aura/env.cc
+++ b/ui/aura/env.cc
@@ -26,7 +26,8 @@ Env* Env::instance_ = NULL;
 Env::Env()
     : mouse_button_flags_(0),
       is_touch_down_(false),
-      render_white_bg_(true) {
+      render_white_bg_(true),
+      stacking_client_(NULL) {
 }
 
 Env::~Env() {
diff --git a/ui/aura/env.h b/ui/aura/env.h
index ae4f1a6..24d7f4f 100644
--- a/ui/aura/env.h
+++ b/ui/aura/env.h
@@ -9,6 +9,7 @@
 #include "base/message_loop.h"
 #include "base/observer_list.h"
 #include "ui/aura/aura_export.h"
+#include "ui/aura/client/stacking_client.h"
 #include "ui/base/events/event_handler.h"
 #include "ui/base/events/event_target.h"
 #include "ui/gfx/point.h"
@@ -63,6 +64,11 @@ class AURA_EXPORT Env : public ui::EventTarget {
   bool render_white_bg() const { return render_white_bg_; }
   void set_render_white_bg(bool value) { render_white_bg_ = value; }
 
+  client::StackingClient* stacking_client() { return stacking_client_; }
+  void set_stacking_client(client::StackingClient* stacking_client) {
+    stacking_client_ = stacking_client;
+  }
+
   // Returns the native event dispatcher. The result should only be passed to
   // base::RunLoop(dispatcher), or used to dispatch an event by
   // |Dispatch(const NativeEvent&)| on it. It must never be stored.
@@ -96,6 +102,7 @@ class AURA_EXPORT Env : public ui::EventTarget {
   gfx::Point last_mouse_location_;
   bool is_touch_down_;
   bool render_white_bg_;
+  client::StackingClient* stacking_client_;
 
 #if defined(USE_X11)
   DeviceListUpdaterAuraX11 device_list_updater_aurax11_;
diff --git a/ui/aura/test/test_stacking_client.cc b/ui/aura/test/test_stacking_client.cc
index 746ad6c..6dd5dcf 100644
--- a/ui/aura/test/test_stacking_client.cc
+++ b/ui/aura/test/test_stacking_client.cc
@@ -11,11 +11,11 @@ namespace test {
 
 TestStackingClient::TestStackingClient(RootWindow* root_window)
     : root_window_(root_window) {
-  client::SetStackingClient(root_window_, this);
+  client::SetStackingClient(this);
 }
 
 TestStackingClient::~TestStackingClient() {
-  client::SetStackingClient(root_window_, NULL);
+  client::SetStackingClient(NULL);
 }
 
 Window* TestStackingClient::GetDefaultParent(Window* context,
diff --git a/ui/aura/window.cc b/ui/aura/window.cc
index 5999290..9eec35c 100644
--- a/ui/aura/window.cc
+++ b/ui/aura/window.cc
@@ -320,7 +320,8 @@ void Window::SetExternalTexture(ui::Texture* texture) {
 
 void Window::SetDefaultParentByRootWindow(RootWindow* root_window,
                                           const gfx::Rect& bounds_in_screen) {
-  DCHECK(root_window);
+  // TODO(erg): Enable this DCHECK once it is safe.
+  //  DCHECK(root_window);
 
   // Stacking clients are mandatory on RootWindow objects.
   client::StackingClient* client = client::GetStackingClient(root_window);
diff --git a/ui/views/examples/content_client/examples_browser_main_parts.cc b/ui/views/examples/content_client/examples_browser_main_parts.cc
index 1714922a..e353b57 100644
--- a/ui/views/examples/content_client/examples_browser_main_parts.cc
+++ b/ui/views/examples/content_client/examples_browser_main_parts.cc
@@ -22,6 +22,7 @@
 #include "ui/aura/env.h"
 #include "ui/gfx/screen.h"
 #include "ui/views/widget/desktop_aura/desktop_screen.h"
+#include "ui/views/widget/desktop_aura/desktop_stacking_client.h"
 #include "ui/views/widget/native_widget_aura.h"
 #endif
 
@@ -39,6 +40,8 @@ void ExamplesBrowserMainParts::PreMainMessageLoopRun() {
   browser_context_.reset(new content::ShellBrowserContext(false));
 
 #if !defined(OS_CHROMEOS) && defined(USE_AURA)
+  stacking_client_.reset(new DesktopStackingClient);
+  aura::client::SetStackingClient(stacking_client_.get());
   gfx::Screen::SetScreenInstance(
       gfx::SCREEN_TYPE_NATIVE, CreateDesktopScreen());
 #endif
@@ -51,6 +54,7 @@ void ExamplesBrowserMainParts::PostMainMessageLoopRun() {
   browser_context_.reset();
   views_delegate_.reset();
 #if defined(USE_AURA)
+  stacking_client_.reset();
   aura::Env::DeleteInstance();
 #endif
 }
diff --git a/ui/views/examples/content_client/examples_browser_main_parts.h b/ui/views/examples/content_client/examples_browser_main_parts.h
index 932ed72..ec76226 100644
--- a/ui/views/examples/content_client/examples_browser_main_parts.h
+++ b/ui/views/examples/content_client/examples_browser_main_parts.h
@@ -9,6 +9,12 @@
 #include "base/memory/scoped_ptr.h"
 #include "content/public/browser/browser_main_parts.h"
 
+namespace aura {
+namespace client {
+class StackingClient;
+}
+}
+
 namespace content {
 class ShellBrowserContext;
 struct MainFunctionParams;
@@ -38,6 +44,9 @@ class ExamplesBrowserMainParts : public content::BrowserMainParts {
   scoped_ptr<content::ShellBrowserContext> browser_context_;
 
   scoped_ptr<ViewsDelegate> views_delegate_;
+#if defined(USE_AURA)
+  scoped_ptr<aura::client::StackingClient> stacking_client_;
+#endif
 
   DISALLOW_COPY_AND_ASSIGN(ExamplesBrowserMainParts);
 };
diff --git a/ui/views/views.gyp b/ui/views/views.gyp
index d4a6806..8a100fd 100644
--- a/ui/views/views.gyp
+++ b/ui/views/views.gyp
@@ -372,6 +372,8 @@
         'widget/desktop_aura/desktop_screen_win.cc',
         'widget/desktop_aura/desktop_screen_win.h',
         'widget/desktop_aura/desktop_screen_x11.cc',
+        'widget/desktop_aura/desktop_stacking_client.cc',
+        'widget/desktop_aura/desktop_stacking_client.h',
         'widget/desktop_aura/x11_desktop_handler.cc',
         'widget/desktop_aura/x11_desktop_handler.h',
         'widget/desktop_aura/x11_desktop_window_move_client.cc',
diff --git a/ui/views/widget/desktop_aura/desktop_stacking_client.cc b/ui/views/widget/desktop_aura/desktop_stacking_client.cc
new file mode 100644
index 0000000..fc7ecb0
--- /dev/null
+++ b/ui/views/widget/desktop_aura/desktop_stacking_client.cc
@@ -0,0 +1,64 @@
+// 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 "ui/views/widget/desktop_aura/desktop_stacking_client.h"
+
+#include "ui/aura/client/activation_client.h"
+#include "ui/aura/client/default_capture_client.h"
+#include "ui/aura/focus_manager.h"
+#include "ui/aura/root_window.h"
+#include "ui/aura/window.h"
+#include "ui/views/corewm/compound_event_filter.h"
+#include "ui/views/corewm/input_method_event_filter.h"
+#include "ui/views/widget/desktop_aura/desktop_activation_client.h"
+
+namespace views {
+
+DesktopStackingClient::DesktopStackingClient()
+    : window_event_filter_(NULL) {
+  aura::client::SetStackingClient(this);
+}
+
+DesktopStackingClient::~DesktopStackingClient() {
+  if (window_event_filter_)
+    window_event_filter_->RemoveHandler(input_method_filter_.get());
+
+  aura::client::SetStackingClient(NULL);
+}
+
+aura::Window* DesktopStackingClient::GetDefaultParent(aura::Window* context,
+                                                      aura::Window* window,
+                                                      const gfx::Rect& bounds) {
+  if (!null_parent_.get())
+    CreateNULLParent();
+
+  return null_parent_.get();
+}
+
+void DesktopStackingClient::CreateNULLParent() {
+  focus_client_.reset(new aura::FocusManager);
+
+  null_parent_.reset(new aura::RootWindow(
+      aura::RootWindow::CreateParams(gfx::Rect(100, 100))));
+  null_parent_->Init();
+  aura::client::SetFocusClient(null_parent_.get(), focus_client_.get());
+
+  activation_client_.reset(new DesktopActivationClient(null_parent_.get()));
+
+  window_event_filter_ = new corewm::CompoundEventFilter;
+  null_parent_->SetEventFilter(window_event_filter_);
+
+  input_method_filter_.reset(new corewm::InputMethodEventFilter(
+                                 null_parent_->GetAcceleratedWidget()));
+  input_method_filter_->SetInputMethodPropertyInRootWindow(null_parent_.get());
+  window_event_filter_->AddHandler(input_method_filter_.get());
+
+  capture_client_.reset(
+      new aura::client::DefaultCaptureClient(null_parent_.get()));
+
+  // Hide the window so we don't attempt to draw to it and what not.
+  null_parent_->Hide();
+}
+
+}  // namespace views
diff --git a/ui/views/widget/desktop_aura/desktop_stacking_client.h b/ui/views/widget/desktop_aura/desktop_stacking_client.h
new file mode 100644
index 0000000..56abc60
--- /dev/null
+++ b/ui/views/widget/desktop_aura/desktop_stacking_client.h
@@ -0,0 +1,65 @@
+// 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.
+
+#ifndef UI_VIEWS_WIDGET_DESKTOP_AURA_DESKTOP_STACKING_CLIENT_H_
+#define UI_VIEWS_WIDGET_DESKTOP_AURA_DESKTOP_STACKING_CLIENT_H_
+
+#include "ui/aura/client/stacking_client.h"
+
+#include "base/basictypes.h"
+#include "base/compiler_specific.h"
+#include "base/memory/scoped_ptr.h"
+#include "ui/views/views_export.h"
+
+namespace aura {
+class RootWindow;
+class Window;
+namespace client {
+class DefaultCaptureClient;
+class FocusClient;
+}
+}
+
+namespace views {
+class DesktopActivationClient;
+namespace corewm {
+class CompoundEventFilter;
+class InputMethodEventFilter;
+}
+
+// A stacking client for the desktop; always sets the default parent to the
+// RootWindow of the passed in Window.
+class VIEWS_EXPORT DesktopStackingClient : public aura::client::StackingClient {
+ public:
+  DesktopStackingClient();
+  virtual ~DesktopStackingClient();
+
+  // Overridden from aura::client::StackingClient:
+  virtual aura::Window* GetDefaultParent(aura::Window* context,
+                                         aura::Window* window,
+                                         const gfx::Rect& bounds) OVERRIDE;
+
+ private:
+  void CreateNULLParent();
+
+  // Windows with NULL parents are parented to this.
+  scoped_ptr<aura::RootWindow> null_parent_;
+
+  // All the member variables below are necessary for the NULL parent root
+  // window to function.
+  scoped_ptr<aura::client::FocusClient> focus_client_;
+  // Depends on focus_manager_.
+  scoped_ptr<DesktopActivationClient> activation_client_;
+
+  scoped_ptr<corewm::InputMethodEventFilter> input_method_filter_;
+  corewm::CompoundEventFilter* window_event_filter_;
+
+  scoped_ptr<aura::client::DefaultCaptureClient> capture_client_;
+
+  DISALLOW_COPY_AND_ASSIGN(DesktopStackingClient);
+};
+
+}  // namespace views
+
+#endif  // UI_VIEWS_WIDGET_DESKTOP_AURA_DESKTOP_STACKING_CLIENT_H_
diff --git a/ui/views/widget/native_widget_aura.cc b/ui/views/widget/native_widget_aura.cc
index 1888378..5089485 100644
--- a/ui/views/widget/native_widget_aura.cc
+++ b/ui/views/widget/native_widget_aura.cc
@@ -136,8 +136,15 @@ void NativeWidgetAura::InitNativeWidget(const Widget::InitParams& params) {
   if (parent) {
     parent->AddChild(window_);
   } else {
-    window_->SetDefaultParentByRootWindow(context->GetRootWindow(),
-                                          window_bounds);
+    // TODO(erg): Once I've threaded context through chrome, uncomment this
+    // check, which currently fails on the NULL == NULL case.
+    //
+    // DCHECK_NE(params.GetParent(), params.context);
+
+    // TODO(erg): Remove this NULL check once we've made everything in views
+    // actually pass us a context.
+    aura::RootWindow* root_window = context ? context->GetRootWindow() : NULL;
+    window_->SetDefaultParentByRootWindow(root_window, window_bounds);
   }
 
   // Wait to set the bounds until we have a parent. That way we can know our
diff --git a/ui/views/widget/widget.cc b/ui/views/widget/widget.cc
index 8194e5a..8a1923d 100644
--- a/ui/views/widget/widget.cc
+++ b/ui/views/widget/widget.cc
@@ -221,15 +221,8 @@ Widget::~Widget() {
 
 // static
 Widget* Widget::CreateWindow(WidgetDelegate* delegate) {
-  return CreateWindowWithBounds(delegate, gfx::Rect());
-}
-
-// static
-Widget* Widget::CreateWindowWithBounds(WidgetDelegate* delegate,
-                                       const gfx::Rect& bounds) {
   Widget* widget = new Widget;
   Widget::InitParams params;
-  params.bounds = bounds;
   params.delegate = delegate;
   params.top_level = true;
   widget->Init(params);
@@ -237,6 +230,12 @@ Widget* Widget::CreateWindowWithBounds(WidgetDelegate* delegate,
 }
 
 // static
+Widget* Widget::CreateWindowWithBounds(WidgetDelegate* delegate,
+                                       const gfx::Rect& bounds) {
+  return CreateWindowWithParentAndBounds(delegate, NULL, bounds);
+}
+
+// static
 Widget* Widget::CreateWindowWithParent(WidgetDelegate* delegate,
                                        gfx::NativeWindow parent) {
   return CreateWindowWithParentAndBounds(delegate, parent, gfx::Rect());