Change GetContainer to take a root window

Update the use of GetContainer to use the correct root window.

BUG=123160
TEST=no functional change. all tests must pass.

Review URL: https://chromiumcodereview.appspot.com/10540076

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@141384 0039d316-1c4b-4281-b951-d872f2087c98

46 files changed, 311 insertions, 200 deletions

diff --git a/ash/accelerators/accelerator_controller.cc b/ash/accelerators/accelerator_controller.cc
index 4dca2ce..b3435d3 100644
--- a/ash/accelerators/accelerator_controller.cc
+++ b/ash/accelerators/accelerator_controller.cc
@@ -42,44 +42,45 @@
 #include "chromeos/monitor/output_configurator.h"
 #endif  // defined(OS_CHROMEOS)
 
+namespace ash {
 namespace {
 
-bool HandleCycleWindowMRU(ash::WindowCycleController::Direction direction,
+bool HandleCycleWindowMRU(WindowCycleController::Direction direction,
                           bool is_alt_down) {
-  ash::Shell::GetInstance()->
+  Shell::GetInstance()->
       window_cycle_controller()->HandleCycleWindow(direction, is_alt_down);
   // Always report we handled the key, even if the window didn't change.
   return true;
 }
 
-void HandleCycleWindowLinear(ash::CycleDirection direction) {
-  ash::Shell::GetInstance()->launcher()->CycleWindowLinear(direction);
+void HandleCycleWindowLinear(CycleDirection direction) {
+  Shell::GetInstance()->launcher()->CycleWindowLinear(direction);
 }
 
 #if defined(OS_CHROMEOS)
 bool HandleLock() {
-  ash::Shell::GetInstance()->delegate()->LockScreen();
+  Shell::GetInstance()->delegate()->LockScreen();
   return true;
 }
 
 bool HandleFileManager() {
-  ash::Shell::GetInstance()->delegate()->OpenFileManager();
+  Shell::GetInstance()->delegate()->OpenFileManager();
   return true;
 }
 
 bool HandleCrosh() {
-  ash::Shell::GetInstance()->delegate()->OpenCrosh();
+  Shell::GetInstance()->delegate()->OpenCrosh();
   return true;
 }
 
 bool HandleToggleSpokenFeedback() {
-  ash::Shell::GetInstance()->delegate()->ToggleSpokenFeedback();
+  Shell::GetInstance()->delegate()->ToggleSpokenFeedback();
   return true;
 }
 #endif
 
 bool HandleExit() {
-  ash::ShellDelegate* delegate = ash::Shell::GetInstance()->delegate();
+  ShellDelegate* delegate = Shell::GetInstance()->delegate();
   if (!delegate)
     return false;
   delegate->Exit();
@@ -87,12 +88,12 @@ bool HandleExit() {
 }
 
 bool HandleNewTab() {
-  ash::Shell::GetInstance()->delegate()->NewTab();
+  Shell::GetInstance()->delegate()->NewTab();
   return true;
 }
 
 bool HandleNewWindow(bool is_incognito) {
-  ash::ShellDelegate* delegate = ash::Shell::GetInstance()->delegate();
+  ShellDelegate* delegate = Shell::GetInstance()->delegate();
   if (!delegate)
     return false;
   delegate->NewWindow(is_incognito);
@@ -100,19 +101,20 @@ bool HandleNewWindow(bool is_incognito) {
 }
 
 bool HandleRestoreTab() {
-  ash::Shell::GetInstance()->delegate()->RestoreTab();
+  Shell::GetInstance()->delegate()->RestoreTab();
   return true;
 }
 
 bool HandleShowTaskManager() {
-  ash::Shell::GetInstance()->delegate()->ShowTaskManager();
+  Shell::GetInstance()->delegate()->ShowTaskManager();
   return true;
 }
 
 // Rotates the default window container.
 bool HandleRotateWindows() {
-  aura::Window* target = ash::Shell::GetInstance()->GetContainer(
-        ash::internal::kShellWindowId_DefaultContainer);
+  aura::Window* target = Shell::GetContainer(
+      Shell::GetPrimaryRootWindow(),
+      internal::kShellWindowId_DefaultContainer);
   scoped_ptr<ui::LayerAnimationSequence> screen_rotation(
       new ui::LayerAnimationSequence(new ui::ScreenRotation(360)));
   target->layer()->GetAnimator()->StartAnimation(
@@ -142,36 +144,36 @@ bool HandleRotateScreen() {
     case 13: delta = 180; break;
   }
   i = (i + 1) % 14;
-  ash::Shell::GetPrimaryRootWindow()->layer()->GetAnimator()->
+  Shell::GetPrimaryRootWindow()->layer()->GetAnimator()->
       set_preemption_strategy(ui::LayerAnimator::REPLACE_QUEUED_ANIMATIONS);
   scoped_ptr<ui::LayerAnimationSequence> screen_rotation(
       new ui::LayerAnimationSequence(new ui::ScreenRotation(delta)));
-  screen_rotation->AddObserver(ash::Shell::GetPrimaryRootWindow());
-  ash::Shell::GetPrimaryRootWindow()->layer()->GetAnimator()->StartAnimation(
+  screen_rotation->AddObserver(Shell::GetPrimaryRootWindow());
+  Shell::GetPrimaryRootWindow()->layer()->GetAnimator()->StartAnimation(
       screen_rotation.release());
   return true;
 }
 
 bool HandleToggleDesktopBackgroundMode() {
-  ash::DesktopBackgroundController* desktop_background_controller =
-      ash::Shell::GetInstance()->desktop_background_controller();
+  DesktopBackgroundController* desktop_background_controller =
+      Shell::GetInstance()->desktop_background_controller();
   if (desktop_background_controller->desktop_background_mode() ==
-      ash::DesktopBackgroundController::BACKGROUND_IMAGE) {
+      DesktopBackgroundController::BACKGROUND_IMAGE) {
     desktop_background_controller->SetDesktopBackgroundSolidColorMode();
   } else {
-    ash::Shell::GetInstance()->user_wallpaper_delegate()->
+    Shell::GetInstance()->user_wallpaper_delegate()->
         SetLoggedInUserWallpaper();
   }
   return true;
 }
 
 bool HandleToggleRootWindowFullScreen() {
-  ash::Shell::GetPrimaryRootWindow()->ToggleFullScreen();
+  Shell::GetPrimaryRootWindow()->ToggleFullScreen();
   return true;
 }
 
 bool HandlePrintLayerHierarchy() {
-  aura::RootWindow* root_window = ash::Shell::GetPrimaryRootWindow();
+  aura::RootWindow* root_window = Shell::GetPrimaryRootWindow();
   ui::PrintLayerHierarchy(root_window->layer(),
                           root_window->last_mouse_location());
   return true;
@@ -180,15 +182,16 @@ bool HandlePrintLayerHierarchy() {
 void PrintWindowHierarchy(aura::Window* window, int indent) {
   std::string indent_str(indent, ' ');
   DLOG(INFO) << indent_str << window->name() << " type " << window->type()
-      << (ash::wm::IsActiveWindow(window) ? "active" : "");
+      << (wm::IsActiveWindow(window) ? "active" : "");
   for (size_t i = 0; i < window->children().size(); ++i)
     PrintWindowHierarchy(window->children()[i], indent + 3);
 }
 
 bool HandlePrintWindowHierarchy() {
   DLOG(INFO) << "Window hierarchy:";
-  aura::Window* container = ash::Shell::GetInstance()->GetContainer(
-      ash::internal::kShellWindowId_DefaultContainer);
+  aura::Window* container =
+      Shell::GetContainer(Shell::GetPrimaryRootWindow(),
+                          internal::kShellWindowId_DefaultContainer);
   PrintWindowHierarchy(container, 0);
   return true;
 }
@@ -197,8 +200,6 @@ bool HandlePrintWindowHierarchy() {
 
 }  // namespace
 
-namespace ash {
-
 ////////////////////////////////////////////////////////////////////////////////
 // AcceleratorController, public:
 
diff --git a/ash/accelerators/accelerator_filter_unittest.cc b/ash/accelerators/accelerator_filter_unittest.cc
index 3240f4d..723960a 100644
--- a/ash/accelerators/accelerator_filter_unittest.cc
+++ b/ash/accelerators/accelerator_filter_unittest.cc
@@ -76,7 +76,8 @@ TEST_F(AcceleratorFilterTest, TestFilterWithoutFocus) {
 
 // Tests if AcceleratorFilter works as expected with a focused window.
 TEST_F(AcceleratorFilterTest, TestFilterWithFocus) {
-  aura::Window* default_container = Shell::GetInstance()->GetContainer(
+  aura::Window* default_container = Shell::GetContainer(
+      Shell::GetPrimaryRootWindow(),
       internal::kShellWindowId_DefaultContainer);
   aura::test::TestWindowDelegate test_delegate;
   scoped_ptr<aura::Window> window(aura::test::CreateTestWindowWithDelegate(
diff --git a/ash/accelerators/nested_dispatcher_controller_unittest.cc b/ash/accelerators/nested_dispatcher_controller_unittest.cc
index 800a27d..3837ff8 100644
--- a/ash/accelerators/nested_dispatcher_controller_unittest.cc
+++ b/ash/accelerators/nested_dispatcher_controller_unittest.cc
@@ -106,7 +106,8 @@ typedef AshTestBase NestedDispatcherTest;
 // Aura window below lock screen in z order.
 TEST_F(NestedDispatcherTest, AssociatedWindowBelowLockScreen) {
   MockDispatcher inner_dispatcher;
-  aura::Window* default_container = Shell::GetInstance()->GetContainer(
+  aura::Window* default_container = Shell::GetContainer(
+      Shell::GetPrimaryRootWindow(),
       internal::kShellWindowId_DefaultContainer);
   scoped_ptr<aura::Window> associated_window(aura::test::CreateTestWindowWithId(
       0, default_container));
@@ -126,7 +127,8 @@ TEST_F(NestedDispatcherTest, AssociatedWindowBelowLockScreen) {
 TEST_F(NestedDispatcherTest, AssociatedWindowAboveLockScreen) {
   MockDispatcher inner_dispatcher;
 
-  aura::Window* default_container = Shell::GetInstance()->GetContainer(
+  aura::Window* default_container = Shell::GetContainer(
+      Shell::GetPrimaryRootWindow(),
       internal::kShellWindowId_DefaultContainer);
   scoped_ptr<aura::Window>mock_lock_container(
       aura::test::CreateTestWindowWithId(0, default_container));
diff --git a/ash/focus_cycler_unittest.cc b/ash/focus_cycler_unittest.cc
index a666928..3dd2482 100644
--- a/ash/focus_cycler_unittest.cc
+++ b/ash/focus_cycler_unittest.cc
@@ -49,9 +49,9 @@ TEST_F(FocusCyclerTest, CycleFocusBrowserOnly) {
   scoped_ptr<FocusCycler> focus_cycler(new FocusCycler());
 
   // Create a single test window.
-  Window* default_container =
-      ash::Shell::GetInstance()->GetContainer(
-          internal::kShellWindowId_DefaultContainer);
+  Window* default_container = Shell::GetContainer(
+      Shell::GetPrimaryRootWindow(),
+      internal::kShellWindowId_DefaultContainer);
   scoped_ptr<Window> window0(CreateTestWindowWithId(0, default_container));
   wm::ActivateWindow(window0.get());
   EXPECT_TRUE(wm::IsActiveWindow(window0.get()));
@@ -79,9 +79,9 @@ TEST_F(FocusCyclerTest, CycleFocusForward) {
   launcher->SetFocusCycler(focus_cycler.get());
 
   // Create a single test window.
-  Window* default_container =
-      ash::Shell::GetInstance()->GetContainer(
-          internal::kShellWindowId_DefaultContainer);
+  Window* default_container = Shell::GetContainer(
+      Shell::GetPrimaryRootWindow(),
+      internal::kShellWindowId_DefaultContainer);
   scoped_ptr<Window> window0(CreateTestWindowWithId(0, default_container));
   wm::ActivateWindow(window0.get());
   EXPECT_TRUE(wm::IsActiveWindow(window0.get()));
@@ -117,9 +117,9 @@ TEST_F(FocusCyclerTest, CycleFocusBackward) {
   launcher->SetFocusCycler(focus_cycler.get());
 
   // Create a single test window.
-  Window* default_container =
-      ash::Shell::GetInstance()->GetContainer(
-          internal::kShellWindowId_DefaultContainer);
+  Window* default_container = Shell::GetContainer(
+      Shell::GetPrimaryRootWindow(),
+      internal::kShellWindowId_DefaultContainer);
   scoped_ptr<Window> window0(CreateTestWindowWithId(0, default_container));
   wm::ActivateWindow(window0.get());
   EXPECT_TRUE(wm::IsActiveWindow(window0.get()));
@@ -186,9 +186,9 @@ TEST_F(FocusCyclerLauncherTest, CycleFocusForwardInvisible) {
   launcher->SetFocusCycler(focus_cycler.get());
 
   // Create a single test window.
-  Window* default_container =
-      ash::Shell::GetInstance()->GetContainer(
-          internal::kShellWindowId_DefaultContainer);
+  Window* default_container = Shell::GetContainer(
+      Shell::GetPrimaryRootWindow(),
+      internal::kShellWindowId_DefaultContainer);
   scoped_ptr<Window> window0(CreateTestWindowWithId(0, default_container));
   wm::ActivateWindow(window0.get());
   EXPECT_TRUE(wm::IsActiveWindow(window0.get()));
@@ -220,9 +220,9 @@ TEST_F(FocusCyclerLauncherTest, CycleFocusBackwardInvisible) {
   launcher->SetFocusCycler(focus_cycler.get());
 
   // Create a single test window.
-  Window* default_container =
-      ash::Shell::GetInstance()->GetContainer(
-          internal::kShellWindowId_DefaultContainer);
+  Window* default_container = Shell::GetInstance()->GetContainer(
+      Shell::GetPrimaryRootWindow(),
+      internal::kShellWindowId_DefaultContainer);
   scoped_ptr<Window> window0(CreateTestWindowWithId(0, default_container));
   wm::ActivateWindow(window0.get());
   EXPECT_TRUE(wm::IsActiveWindow(window0.get()));
diff --git a/ash/launcher/launcher.cc b/ash/launcher/launcher.cc
index aa0024b..f8314bc 100644
--- a/ash/launcher/launcher.cc
+++ b/ash/launcher/launcher.cc
@@ -116,7 +116,8 @@ Launcher::Launcher(aura::Window* window_container)
   params.layer_type = ui::LAYER_SOLID_COLOR;
   params.transparent = true;
   params.ownership = views::Widget::InitParams::WIDGET_OWNS_NATIVE_WIDGET;
-  params.parent = Shell::GetInstance()->GetContainer(
+  params.parent = Shell::GetContainer(
+      window_container_->GetRootWindow(),
       ash::internal::kShellWindowId_LauncherContainer);
   launcher_view_ = new internal::LauncherView(model_.get(), delegate_.get());
   launcher_view_->Init();
diff --git a/ash/shell.cc b/ash/shell.cc
index 51cd7bf..b7f7443 100644
--- a/ash/shell.cc
+++ b/ash/shell.cc
@@ -704,15 +704,33 @@ aura::RootWindow* Shell::GetPrimaryRootWindow() {
   return GetInstance()->root_window_.get();
 }
 
+// static
 aura::RootWindow* Shell::GetActiveRootWindow() {
   return GetInstance()->active_root_window_;
 }
 
+// static
 aura::RootWindow* Shell::GetRootWindowAt(const gfx::Point& point) {
   // TODO(oshima): Support multiple root windows.
   return GetPrimaryRootWindow();
 }
 
+// static
+aura::Window* Shell::GetContainer(aura::RootWindow* root_window,
+                                  int container_id) {
+  return root_window->GetChildById(container_id);
+}
+
+// static
+std::vector<aura::Window*> Shell::GetAllContainers(int container_id) {
+  // TODO(oshima): Support multiple root windows.
+  std::vector<aura::Window*> containers;
+  aura::Window* container = GetPrimaryRootWindow()->GetChildById(container_id);
+  if (container)
+    containers.push_back(container);
+  return containers;
+}
+
 void Shell::Init() {
   // Install the custom factory first so that views::FocusManagers for Tray,
   // Launcher, and WallPaper could be created by the factory.
@@ -870,15 +888,6 @@ void Shell::Init() {
   screen_dimmer_.reset(new internal::ScreenDimmer(root_window));
 }
 
-aura::Window* Shell::GetContainer(int container_id) {
-  return const_cast<aura::Window*>(
-      const_cast<const Shell*>(this)->GetContainer(container_id));
-}
-
-const aura::Window* Shell::GetContainer(int container_id) const {
-  return GetPrimaryRootWindow()->GetChildById(container_id);
-}
-
 void Shell::AddEnvEventFilter(aura::EventFilter* filter) {
   env_filter_->AddFilter(filter);
 }
@@ -917,7 +926,9 @@ bool Shell::IsScreenLocked() const {
 }
 
 bool Shell::IsModalWindowOpen() const {
+  // TODO(oshima): Walk though all root windows.
   const aura::Window* modal_container = GetContainer(
+      GetPrimaryRootWindow(),
       internal::kShellWindowId_SystemModalContainer);
   return !modal_container->children().empty();
 }
@@ -967,8 +978,9 @@ void Shell::CreateLauncher() {
   if (launcher_.get())
     return;
 
-  aura::Window* default_container =
-      GetContainer(internal::kShellWindowId_DefaultContainer);
+  aura::Window* default_container = GetContainer(
+      GetPrimaryRootWindow(),
+      internal::kShellWindowId_DefaultContainer);
   launcher_.reset(new Launcher(default_container));
 
   launcher_->SetFocusCycler(focus_cycler_.get());
@@ -1044,17 +1056,20 @@ void Shell::InitLayoutManagers() {
 
   internal::ShelfLayoutManager* shelf_layout_manager =
       new internal::ShelfLayoutManager(status_area_widget_);
-  GetContainer(internal::kShellWindowId_LauncherContainer)->
+  GetContainer(
+      GetPrimaryRootWindow(),
+      internal::kShellWindowId_LauncherContainer)->
       SetLayoutManager(shelf_layout_manager);
   shelf_ = shelf_layout_manager;
 
   internal::StatusAreaLayoutManager* status_area_layout_manager =
       new internal::StatusAreaLayoutManager(shelf_layout_manager);
-  GetContainer(internal::kShellWindowId_StatusContainer)->
+  GetContainer(GetPrimaryRootWindow(),
+               internal::kShellWindowId_StatusContainer)->
       SetLayoutManager(status_area_layout_manager);
 
-  aura::Window* default_container =
-      GetContainer(internal::kShellWindowId_DefaultContainer);
+  aura::Window* default_container = GetContainer(
+      GetPrimaryRootWindow(), internal::kShellWindowId_DefaultContainer);
   // Workspace manager has its own layout managers.
   workspace_controller_.reset(
       new internal::WorkspaceController(default_container));
@@ -1062,8 +1077,8 @@ void Shell::InitLayoutManagers() {
   shelf_layout_manager->set_workspace_manager(
       workspace_controller_->workspace_manager());
 
-  aura::Window* always_on_top_container =
-      GetContainer(internal::kShellWindowId_AlwaysOnTopContainer);
+  aura::Window* always_on_top_container = GetContainer(
+      GetPrimaryRootWindow(), internal::kShellWindowId_AlwaysOnTopContainer);
   always_on_top_container->SetLayoutManager(
       new internal::BaseLayoutManager(
           always_on_top_container->GetRootWindow()));
@@ -1072,6 +1087,7 @@ void Shell::InitLayoutManagers() {
   if (CommandLine::ForCurrentProcess()->
       HasSwitch(switches::kAuraPanelManager)) {
     aura::Window* panel_container = GetContainer(
+        GetPrimaryRootWindow(),
         internal::kShellWindowId_PanelContainer);
     panel_layout_manager_ =
         new internal::PanelLayoutManager(panel_container);
diff --git a/ash/shell.h b/ash/shell.h
index 27ce5e2..5848d29 100644
--- a/ash/shell.h
+++ b/ash/shell.h
@@ -160,6 +160,13 @@ class ASH_EXPORT Shell : aura::CursorDelegate {
   // point.
   static aura::RootWindow* GetRootWindowAt(const gfx::Point& point);
 
+  static aura::Window* GetContainer(aura::RootWindow* root_window,
+                                    int container_id);
+
+  // Returns the list of containers that match |container_id| in
+  // all root windows.
+  static std::vector<aura::Window*> GetAllContainers(int container_id);
+
   void set_active_root_window(aura::RootWindow* active_root_window) {
     active_root_window_ = active_root_window;
   }
@@ -168,9 +175,6 @@ class ASH_EXPORT Shell : aura::CursorDelegate {
     return root_window_layout_;
   }
 
-  aura::Window* GetContainer(int container_id);
-  const aura::Window* GetContainer(int container_id) const;
-
   // Adds or removes |filter| from the aura::Env's CompoundEventFilter.
   void AddEnvEventFilter(aura::EventFilter* filter);
   void RemoveEnvEventFilter(aura::EventFilter* filter);
diff --git a/ash/shell/lock_view.cc b/ash/shell/lock_view.cc
index 3c90679..6b72fce 100644
--- a/ash/shell/lock_view.cc
+++ b/ash/shell/lock_view.cc
@@ -91,9 +91,9 @@ void CreateLockScreen() {
                             (root_window_size.height() - ps.height()) / 2,
                             ps.width(), ps.height());
   params.delegate = lock_view;
-  params.parent =
-      Shell::GetInstance()->GetContainer(
-          ash::internal::kShellWindowId_LockScreenContainer);
+  params.parent = Shell::GetContainer(
+      Shell::GetPrimaryRootWindow(),
+      internal::kShellWindowId_LockScreenContainer);
   widget->Init(params);
   widget->SetContentsView(lock_view);
   widget->Show();
diff --git a/ash/shell/window_watcher.cc b/ash/shell/window_watcher.cc
index cbac740..a3d99f1 100644
--- a/ash/shell/window_watcher.cc
+++ b/ash/shell/window_watcher.cc
@@ -15,8 +15,9 @@ namespace shell {
 
 WindowWatcher::WindowWatcher()
     : window_(ash::Shell::GetInstance()->launcher()->window_container()),
-      panel_container_(ash::Shell::GetInstance()->GetContainer(
-          ash::internal::kShellWindowId_PanelContainer)) {
+      panel_container_(ash::Shell::GetContainer(
+          Shell::GetPrimaryRootWindow(),
+          internal::kShellWindowId_PanelContainer)) {
   window_->AddObserver(this);
   panel_container_->AddObserver(this);
 }
diff --git a/ash/shell_unittest.cc b/ash/shell_unittest.cc
index 59d17c7..a5e7939 100644
--- a/ash/shell_unittest.cc
+++ b/ash/shell_unittest.cc
@@ -33,44 +33,46 @@ views::Widget* CreateTestWindow(const views::Widget::InitParams& params) {
 }
 
 aura::Window* GetDefaultContainer() {
-  return Shell::GetInstance()->GetContainer(
-        ash::internal::kShellWindowId_DefaultContainer);
+  return Shell::GetContainer(
+      Shell::GetPrimaryRootWindow(),
+      internal::kShellWindowId_DefaultContainer);
 }
 
 aura::Window* GetAlwaysOnTopContainer() {
-  return Shell::GetInstance()->GetContainer(
-        ash::internal::kShellWindowId_AlwaysOnTopContainer);
+  return Shell::GetContainer(
+      Shell::GetPrimaryRootWindow(),
+      internal::kShellWindowId_AlwaysOnTopContainer);
 }
 
 // Expect ALL the containers!
 void ExpectAllContainers() {
-  Shell* shell = Shell::GetInstance();
-  EXPECT_TRUE(
-      shell->GetContainer(internal::kShellWindowId_DesktopBackgroundContainer));
-  EXPECT_TRUE(
-      shell->GetContainer(internal::kShellWindowId_DefaultContainer));
-  EXPECT_TRUE(
-      shell->GetContainer(internal::kShellWindowId_AlwaysOnTopContainer));
-  EXPECT_TRUE(
-      shell->GetContainer(internal::kShellWindowId_PanelContainer));
-  EXPECT_TRUE(
-      shell->GetContainer(internal::kShellWindowId_LauncherContainer));
-  EXPECT_TRUE(
-      shell->GetContainer(internal::kShellWindowId_SystemModalContainer));
-  EXPECT_TRUE(
-      shell->GetContainer(internal::kShellWindowId_LockScreenContainer));
-  EXPECT_TRUE(
-      shell->GetContainer(internal::kShellWindowId_LockSystemModalContainer));
-  EXPECT_TRUE(
-      shell->GetContainer(internal::kShellWindowId_StatusContainer));
-  EXPECT_TRUE(
-      shell->GetContainer(internal::kShellWindowId_MenuContainer));
-  EXPECT_TRUE(shell->GetContainer(
-      internal::kShellWindowId_DragImageAndTooltipContainer));
-  EXPECT_TRUE(
-      shell->GetContainer(internal::kShellWindowId_SettingBubbleContainer));
-  EXPECT_TRUE(
-      shell->GetContainer(internal::kShellWindowId_OverlayContainer));
+  aura::RootWindow* root_window = Shell::GetPrimaryRootWindow();
+  EXPECT_TRUE(Shell::GetContainer(
+      root_window, internal::kShellWindowId_DesktopBackgroundContainer));
+  EXPECT_TRUE(Shell::GetContainer(
+      root_window, internal::kShellWindowId_DefaultContainer));
+  EXPECT_TRUE(Shell::GetContainer(
+      root_window, internal::kShellWindowId_AlwaysOnTopContainer));
+  EXPECT_TRUE(Shell::GetContainer(
+      root_window, internal::kShellWindowId_PanelContainer));
+  EXPECT_TRUE(Shell::GetContainer(
+      root_window, internal::kShellWindowId_LauncherContainer));
+  EXPECT_TRUE(Shell::GetContainer(
+      root_window, internal::kShellWindowId_SystemModalContainer));
+  EXPECT_TRUE(Shell::GetContainer(
+      root_window, internal::kShellWindowId_LockScreenContainer));
+  EXPECT_TRUE(Shell::GetContainer(
+      root_window, internal::kShellWindowId_LockSystemModalContainer));
+  EXPECT_TRUE(Shell::GetContainer(
+      root_window, internal::kShellWindowId_StatusContainer));
+  EXPECT_TRUE(Shell::GetContainer(
+      root_window, internal::kShellWindowId_MenuContainer));
+  EXPECT_TRUE(Shell::GetContainer(
+      root_window, internal::kShellWindowId_DragImageAndTooltipContainer));
+  EXPECT_TRUE(Shell::GetContainer(
+      root_window, internal::kShellWindowId_SettingBubbleContainer));
+  EXPECT_TRUE(Shell::GetContainer(
+      root_window, internal::kShellWindowId_OverlayContainer));
 }
 
 void TestCreateWindow(views::Widget::InitParams::Type type,
@@ -186,8 +188,9 @@ TEST_F(ShellTest, CreateModalWindow) {
   modal_widget->Show();
 
   // It should be in modal container.
-  aura::Window* modal_container = Shell::GetInstance()->GetContainer(
-      ash::internal::kShellWindowId_SystemModalContainer);
+  aura::Window* modal_container = Shell::GetContainer(
+      Shell::GetPrimaryRootWindow(),
+      internal::kShellWindowId_SystemModalContainer);
   EXPECT_EQ(modal_container, modal_widget->GetNativeWindow()->parent());
 
   modal_widget->Close();
@@ -207,13 +210,15 @@ TEST_F(ShellTest, CreateLockScreenModalWindow) {
 
   // Create a LockScreen window.
   views::Widget* lock_widget = CreateTestWindow(widget_params);
-  ash::Shell::GetInstance()->GetContainer(
+  ash::Shell::GetContainer(
+      Shell::GetPrimaryRootWindow(),
       ash::internal::kShellWindowId_LockScreenContainer)->
       AddChild(lock_widget->GetNativeView());
   lock_widget->Show();
 
   // It should be in LockScreen container.
-  aura::Window* lock_screen = Shell::GetInstance()->GetContainer(
+  aura::Window* lock_screen = Shell::GetContainer(
+      Shell::GetPrimaryRootWindow(),
       ash::internal::kShellWindowId_LockScreenContainer);
   EXPECT_EQ(lock_screen, lock_widget->GetNativeWindow()->parent());
 
@@ -223,7 +228,8 @@ TEST_F(ShellTest, CreateLockScreenModalWindow) {
   lock_modal_widget->Show();
 
   // It should be in LockScreen modal container.
-  aura::Window* lock_modal_container = Shell::GetInstance()->GetContainer(
+  aura::Window* lock_modal_container = Shell::GetContainer(
+      Shell::GetPrimaryRootWindow(),
       ash::internal::kShellWindowId_LockSystemModalContainer);
   EXPECT_EQ(lock_modal_container,
             lock_modal_widget->GetNativeWindow()->parent());
@@ -234,7 +240,8 @@ TEST_F(ShellTest, CreateLockScreenModalWindow) {
   modal_widget->Show();
 
   // It should be in non-LockScreen modal container.
-  aura::Window* modal_container = Shell::GetInstance()->GetContainer(
+  aura::Window* modal_container = Shell::GetContainer(
+      Shell::GetPrimaryRootWindow(),
       ash::internal::kShellWindowId_SystemModalContainer);
   EXPECT_EQ(modal_container, modal_widget->GetNativeWindow()->parent());
 
diff --git a/ash/system/network/tray_network.cc b/ash/system/network/tray_network.cc
index 98e5c33..be73b5f 100644
--- a/ash/system/network/tray_network.cc
+++ b/ash/system/network/tray_network.cc
@@ -69,7 +69,8 @@ class NonActivatableSettingsBubble : public views::BubbleDelegateView {
   NonActivatableSettingsBubble(views::View* anchor, views::View* content)
       : views::BubbleDelegateView(anchor, views::BubbleBorder::TOP_RIGHT) {
     set_use_focusless(true);
-    set_parent_window(ash::Shell::GetInstance()->GetContainer(
+    set_parent_window(ash::Shell::GetContainer(
+        anchor->GetWidget()->GetNativeWindow()->GetRootWindow(),
         ash::internal::kShellWindowId_SettingBubbleContainer));
     SetLayoutManager(new views::FillLayout());
     AddChildView(content);
diff --git a/ash/system/status_area_widget.cc b/ash/system/status_area_widget.cc
index e5f8ea6..2e66512 100644
--- a/ash/system/status_area_widget.cc
+++ b/ash/system/status_area_widget.cc
@@ -18,7 +18,8 @@ StatusAreaWidget::StatusAreaWidget() {
   views::Widget::InitParams params(
       views::Widget::InitParams::TYPE_WINDOW_FRAMELESS);
   params.delegate = widget_delegate_;
-  params.parent = Shell::GetInstance()->GetContainer(
+  params.parent = Shell::GetContainer(
+      Shell::GetPrimaryRootWindow(),
       ash::internal::kShellWindowId_StatusContainer);
   params.transparent = true;
   Init(params);
diff --git a/ash/system/tray/system_tray_bubble.cc b/ash/system/tray/system_tray_bubble.cc
index 5567b13..6a1f70c 100644
--- a/ash/system/tray/system_tray_bubble.cc
+++ b/ash/system/tray/system_tray_bubble.cc
@@ -297,8 +297,9 @@ SystemTrayBubbleView::SystemTrayBubbleView(
       max_height_(0),
       bubble_width_(bubble_width) {
   set_margin(0);
-  set_parent_window(ash::Shell::GetInstance()->GetContainer(
-      ash::internal::kShellWindowId_SettingBubbleContainer));
+  set_parent_window(Shell::GetContainer(
+      anchor->GetWidget()->GetNativeWindow()->GetRootWindow(),
+      internal::kShellWindowId_SettingBubbleContainer));
   set_notify_enter_exit_on_child(true);
   SetPaintToLayer(true);
   SetFillsBoundsOpaquely(true);
diff --git a/ash/touch/touch_observer_hud.cc b/ash/touch/touch_observer_hud.cc
index b7773a5..2b976d2 100644
--- a/ash/touch/touch_observer_hud.cc
+++ b/ash/touch/touch_observer_hud.cc
@@ -137,7 +137,8 @@ TouchObserverHUD::TouchObserverHUD() {
   params.can_activate = false;
   params.accept_events = false;
   params.bounds = gfx::Rect(content->GetPreferredSize());
-  params.parent = Shell::GetInstance()->GetContainer(
+  params.parent = Shell::GetContainer(
+      Shell::GetPrimaryRootWindow(),
       internal::kShellWindowId_OverlayContainer);
   widget_->Init(params);
   widget_->SetContentsView(content);
diff --git a/ash/wm/activation_controller.cc b/ash/wm/activation_controller.cc
index 2452eb5..668271b 100644
--- a/ash/wm/activation_controller.cc
+++ b/ash/wm/activation_controller.cc
@@ -43,10 +43,6 @@ const int kWindowContainerIds[] = {
     kShellWindowId_StatusContainer,
 };
 
-aura::Window* GetContainer(int id) {
-  return Shell::GetInstance()->GetContainer(id);
-}
-
 // Returns true if children of |window| can be activated.
 // These are the only containers in which windows can receive focus.
 bool SupportsChildActivation(aura::Window* window) {
@@ -310,8 +306,11 @@ aura::Window* ActivationController::GetTopmostWindowToActivate(
   size_t current_container_index = 0;
   // If the container of the window losing focus is in the list, start from that
   // container.
+  aura::RootWindow* root = ignore->GetRootWindow();
+  if (!root)
+    root = Shell::GetActiveRootWindow();
   for (size_t i = 0; ignore && i < arraysize(kWindowContainerIds); i++) {
-    aura::Window* container = GetContainer(kWindowContainerIds[i]);
+    aura::Window* container = Shell::GetContainer(root, kWindowContainerIds[i]);
     if (container && container->Contains(ignore)) {
       current_container_index = i;
       break;
@@ -322,10 +321,14 @@ aura::Window* ActivationController::GetTopmostWindowToActivate(
   aura::Window* window = NULL;
   for (; !window && current_container_index < arraysize(kWindowContainerIds);
        current_container_index++) {
-    aura::Window* container =
-        GetContainer(kWindowContainerIds[current_container_index]);
-    if (container)
-      window = GetTopmostWindowToActivateInContainer(container, ignore);
+
+    aura::Window::Windows containers =
+        Shell::GetAllContainers(kWindowContainerIds[current_container_index]);
+    for (aura::Window::Windows::const_iterator iter = containers.begin();
+         iter != containers.end();
+         ++iter) {
+      window = GetTopmostWindowToActivateInContainer((*iter), ignore);
+    }
   }
   return window;
 }
diff --git a/ash/wm/activation_controller_unittest.cc b/ash/wm/activation_controller_unittest.cc
index 9a1e6f1..98f5195 100644
--- a/ash/wm/activation_controller_unittest.cc
+++ b/ash/wm/activation_controller_unittest.cc
@@ -88,7 +88,7 @@ class GetTopmostWindowToActivateTest : public ActivationControllerTest {
         &delegate_,
         id,
         gfx::Rect(),
-        Shell::GetInstance()->GetContainer(container_id));
+        Shell::GetContainer(Shell::GetPrimaryRootWindow(), container_id));
     delegate->SetWindow(window);
     return window;
   }
diff --git a/ash/wm/app_list_controller.cc b/ash/wm/app_list_controller.cc
index f447b13a..d4c51f1 100644
--- a/ash/wm/app_list_controller.cc
+++ b/ash/wm/app_list_controller.cc
@@ -85,7 +85,9 @@ void AppListController::SetVisible(bool visible) {
     app_list::AppListView* view = new app_list::AppListView(
         Shell::GetInstance()->delegate()->CreateAppListViewDelegate());
     view->InitAsBubble(
-        Shell::GetInstance()->GetContainer(kShellWindowId_AppListContainer),
+        Shell::GetContainer(
+            Shell::GetPrimaryRootWindow(),
+            kShellWindowId_AppListContainer),
         Shell::GetInstance()->launcher()->GetAppListButtonView(),
         GetBubbleArrowLocation());
     SetView(view);
@@ -199,9 +201,11 @@ ui::GestureStatus AppListController::PreHandleGestureEvent(
 // AppListController,  aura::FocusObserver implementation:
 void AppListController::OnWindowFocused(aura::Window* window) {
   if (view_ && is_visible_) {
-    aura::Window* applist_container = Shell::GetInstance()->GetContainer(
+    aura::Window* applist_container = Shell::GetContainer(
+        Shell::GetPrimaryRootWindow(),
         kShellWindowId_AppListContainer);
-    aura::Window* bubble_container = Shell::GetInstance()->GetContainer(
+    aura::Window* bubble_container = Shell::GetContainer(
+        Shell::GetPrimaryRootWindow(),
         kShellWindowId_SettingBubbleContainer);
     if (window->parent() != applist_container &&
         window->parent() != bubble_container) {
diff --git a/ash/wm/base_layout_manager_unittest.cc b/ash/wm/base_layout_manager_unittest.cc
index 2309491..7420d23 100644
--- a/ash/wm/base_layout_manager_unittest.cc
+++ b/ash/wm/base_layout_manager_unittest.cc
@@ -33,7 +33,8 @@ class BaseLayoutManagerTest : public test::AshTestBase {
         Shell::GetPrimaryRootWindow(),
         gfx::Insets(1, 2, 3, 4));
     Shell::GetPrimaryRootWindow()->SetHostSize(gfx::Size(800, 600));
-    aura::Window* default_container = Shell::GetInstance()->GetContainer(
+    aura::Window* default_container = Shell::GetContainer(
+        Shell::GetPrimaryRootWindow(),
         internal::kShellWindowId_DefaultContainer);
     default_container->SetLayoutManager(new internal::BaseLayoutManager(
         Shell::GetPrimaryRootWindow()));
diff --git a/ash/wm/event_client_impl.cc b/ash/wm/event_client_impl.cc
index 58b4385..1804e38 100644
--- a/ash/wm/event_client_impl.cc
+++ b/ash/wm/event_client_impl.cc
@@ -24,12 +24,12 @@ EventClientImpl::~EventClientImpl() {
 bool EventClientImpl::CanProcessEventsWithinSubtree(
     const aura::Window* window) const {
   if (Shell::GetInstance()->IsScreenLocked()) {
-    aura::Window* lock_screen_containers =
-        Shell::GetInstance()->GetContainer(
-            kShellWindowId_LockScreenContainersContainer);
-    aura::Window* lock_screen_related_containers =
-        Shell::GetInstance()->GetContainer(
-            kShellWindowId_LockScreenRelatedContainersContainer);
+    aura::Window* lock_screen_containers = Shell::GetContainer(
+        root_window_,
+        kShellWindowId_LockScreenContainersContainer);
+    aura::Window* lock_screen_related_containers = Shell::GetContainer(
+        root_window_,
+        kShellWindowId_LockScreenRelatedContainersContainer);
     return lock_screen_containers->Contains(window) ||
         lock_screen_related_containers->Contains(window);
   }
diff --git a/ash/wm/frame_painter_unittest.cc b/ash/wm/frame_painter_unittest.cc
index 57ae977..d0b4bdf 100644
--- a/ash/wm/frame_painter_unittest.cc
+++ b/ash/wm/frame_painter_unittest.cc
@@ -20,7 +20,8 @@ using views::ImageButton;
 namespace {
 
 aura::Window* GetDefaultContainer() {
-  return ash::Shell::GetInstance()->GetContainer(
+  return ash::Shell::GetContainer(
+      ash::Shell::GetPrimaryRootWindow(),
       ash::internal::kShellWindowId_DefaultContainer);
 }
 
diff --git a/ash/wm/panel_layout_manager_unittest.cc b/ash/wm/panel_layout_manager_unittest.cc
index a7d0ce3..f1878ca 100644
--- a/ash/wm/panel_layout_manager_unittest.cc
+++ b/ash/wm/panel_layout_manager_unittest.cc
@@ -53,7 +53,8 @@ class PanelLayoutManagerTest : public ash::test::AshTestBase {
   }
 
   aura::Window* GetPanelContainer() {
-    return Shell::GetInstance()->GetContainer(
+    return Shell::GetContainer(
+        Shell::GetPrimaryRootWindow(),
         ash::internal::kShellWindowId_PanelContainer);
   }
 
diff --git a/ash/wm/partial_screenshot_view.cc b/ash/wm/partial_screenshot_view.cc
index 3e492e2..64d9855 100644
--- a/ash/wm/partial_screenshot_view.cc
+++ b/ash/wm/partial_screenshot_view.cc
@@ -41,19 +41,20 @@ void PartialScreenshotView::StartPartialScreenshot(
   views::Widget* widget = new views::Widget;
   PartialScreenshotView* view = new PartialScreenshotView(
       screenshot_delegate);
-
+  aura::RootWindow* root_window = Shell::GetActiveRootWindow();
   views::Widget::InitParams params(
       views::Widget::InitParams::TYPE_WINDOW_FRAMELESS);
   params.transparent = true;
   params.delegate = view;
   // The partial screenshot rectangle has to be at the real top of
   // the screen.
-  params.parent = Shell::GetInstance()->GetContainer(
+  params.parent = Shell::GetContainer(
+      root_window,
       internal::kShellWindowId_OverlayContainer);
 
   widget->Init(params);
   widget->SetContentsView(view);
-  widget->SetBounds(Shell::GetPrimaryRootWindow()->bounds());
+  widget->SetBounds(root_window->bounds());
   widget->GetNativeView()->SetName("PartialScreenshotView");
   widget->StackAtTop();
   widget->Show();
diff --git a/ash/wm/power_button_controller.cc b/ash/wm/power_button_controller.cc
index 8b7deb7..7f2ceac 100644
--- a/ash/wm/power_button_controller.cc
+++ b/ash/wm/power_button_controller.cc
@@ -161,15 +161,17 @@ void RestoreWindow(aura::Window* window) {
 // Fills |containers| with the containers described by |group|.
 void GetContainers(PowerButtonController::ContainerGroup group,
                    aura::Window::Windows* containers) {
-  aura::Window* non_lock_screen_containers =
-      Shell::GetInstance()->GetContainer(
-          internal::kShellWindowId_NonLockScreenContainersContainer);
-  aura::Window* lock_screen_containers =
-      Shell::GetInstance()->GetContainer(
-          internal::kShellWindowId_LockScreenContainersContainer);
-  aura::Window* lock_screen_related_containers =
-      Shell::GetInstance()->GetContainer(
-          internal::kShellWindowId_LockScreenRelatedContainersContainer);
+  aura::RootWindow* root_window = Shell::GetPrimaryRootWindow();
+
+  aura::Window* non_lock_screen_containers = Shell::GetContainer(
+      root_window,
+      internal::kShellWindowId_NonLockScreenContainersContainer);
+  aura::Window* lock_screen_containers = Shell::GetContainer(
+      root_window,
+      internal::kShellWindowId_LockScreenContainersContainer);
+  aura::Window* lock_screen_related_containers = Shell::GetContainer(
+      root_window,
+      internal::kShellWindowId_LockScreenRelatedContainersContainer);
 
   containers->clear();
   switch (group) {
diff --git a/ash/wm/shelf_layout_manager_unittest.cc b/ash/wm/shelf_layout_manager_unittest.cc
index 65606da..d90d05f 100644
--- a/ash/wm/shelf_layout_manager_unittest.cc
+++ b/ash/wm/shelf_layout_manager_unittest.cc
@@ -38,8 +38,9 @@ void StepWidgetLayerAnimatorToEnd(views::Widget* widget) {
 }
 
 ShelfLayoutManager* GetShelfLayoutManager() {
-  aura::Window* window = ash::Shell::GetInstance()->GetContainer(
-      ash::internal::kShellWindowId_LauncherContainer);
+  aura::Window* window = Shell::GetContainer(
+      Shell::GetPrimaryRootWindow(),
+      internal::kShellWindowId_LauncherContainer);
   return static_cast<ShelfLayoutManager*>(window->layout_manager());
 }
 
@@ -63,7 +64,8 @@ class ShelfLayoutManagerTest : public ash::test::AshTestBase {
     window->SetProperty(aura::client::kShowStateKey, ui::SHOW_STATE_NORMAL);
     window->SetType(aura::client::WINDOW_TYPE_NORMAL);
     window->Init(ui::LAYER_TEXTURED);
-    aura::Window* parent = Shell::GetInstance()->GetContainer(
+    aura::Window* parent = Shell::GetContainer(
+        Shell::GetPrimaryRootWindow(),
         internal::kShellWindowId_DefaultContainer);
     window->SetParent(parent);
     return window;
@@ -283,7 +285,8 @@ TEST_F(ShelfLayoutManagerTest, VisibleWhenLockScreenShowing) {
   EXPECT_EQ(root->bounds().bottom() - ShelfLayoutManager::kAutoHideSize,
             shelf->launcher_widget()->GetWindowScreenBounds().y());
 
-  aura::Window* lock_container = Shell::GetInstance()->GetContainer(
+  aura::Window* lock_container = Shell::GetContainer(
+      Shell::GetPrimaryRootWindow(),
       internal::kShellWindowId_LockScreenContainer);
 
   views::Widget* lock_widget = new views::Widget;
diff --git a/ash/wm/stacking_controller.cc b/ash/wm/stacking_controller.cc
index 42aedf6..2f5e975 100644
--- a/ash/wm/stacking_controller.cc
+++ b/ash/wm/stacking_controller.cc
@@ -7,7 +7,9 @@
 #include "ash/shell.h"
 #include "ash/shell_window_ids.h"
 #include "ash/wm/always_on_top_controller.h"
+#include "ash/wm/window_properties.h"
 #include "ui/aura/client/aura_constants.h"
+#include "ui/aura/root_window.h"
 #include "ui/aura/window.h"
 #include "ui/base/ui_base_types.h"
 
@@ -16,7 +18,7 @@ namespace internal {
 namespace {
 
 aura::Window* GetContainerById(int id) {
-  return Shell::GetInstance()->GetContainer(id);
+  return Shell::GetContainer(Shell::GetActiveRootWindow(), id);
 }
 
 aura::Window* GetContainerForWindow(aura::Window* window) {
@@ -42,10 +44,6 @@ bool IsWindowModal(aura::Window* window) {
 
 StackingController::StackingController() {
   aura::client::SetStackingClient(this);
-  always_on_top_controller_.reset(new internal::AlwaysOnTopController);
-  always_on_top_controller_->SetContainers(
-      GetContainerById(internal::kShellWindowId_DefaultContainer),
-      GetContainerById(internal::kShellWindowId_AlwaysOnTopContainer));
 }
 
 StackingController::~StackingController() {
@@ -62,7 +60,7 @@ aura::Window* StackingController::GetDefaultParent(aura::Window* window) {
         return GetSystemModalContainer(window);
       else if (IsWindowModal(window))
         return GetContainerForWindow(window->transient_parent());
-      return always_on_top_controller_->GetContainer(window);
+      return GetAlwaysOnTopController()->GetContainer(window);
     case aura::client::WINDOW_TYPE_PANEL:
       return GetContainerById(internal::kShellWindowId_PanelContainer);
     case aura::client::WINDOW_TYPE_MENU:
@@ -113,5 +111,22 @@ aura::Window* StackingController::GetSystemModalContainer(
   return container;
 }
 
+internal::AlwaysOnTopController*
+StackingController::GetAlwaysOnTopController() {
+  aura::RootWindow* root_window = Shell::GetActiveRootWindow();
+  internal::AlwaysOnTopController* controller =
+      root_window->GetProperty(internal::kAlwaysOnTopControllerKey);
+  if (!controller) {
+    controller = new internal::AlwaysOnTopController;
+    controller->SetContainers(
+        root_window->GetChildById(internal::kShellWindowId_DefaultContainer),
+        root_window->GetChildById(
+            internal::kShellWindowId_AlwaysOnTopContainer));
+    // RootWindow owns the AlwaysOnTopController object.
+    root_window->SetProperty(kAlwaysOnTopControllerKey, controller);
+  }
+  return controller;
+}
+
 }  // namespace internal
 }  // namespace ash
diff --git a/ash/wm/stacking_controller.h b/ash/wm/stacking_controller.h
index 9e38216..5a3676d 100644
--- a/ash/wm/stacking_controller.h
+++ b/ash/wm/stacking_controller.h
@@ -32,7 +32,8 @@ class StackingController : public aura::client::StackingClient {
   // placed in the screen lock modal container.
   aura::Window* GetSystemModalContainer(aura::Window* window) const;
 
-  scoped_ptr<internal::AlwaysOnTopController> always_on_top_controller_;
+  // Returns the AlwaysOnTopController for the current active root window.
+  internal::AlwaysOnTopController* GetAlwaysOnTopController();
 
   DISALLOW_COPY_AND_ASSIGN(StackingController);
 };
diff --git a/ash/wm/system_gesture_event_filter.cc b/ash/wm/system_gesture_event_filter.cc
index e7800fee..98cbac9 100644
--- a/ash/wm/system_gesture_event_filter.cc
+++ b/ash/wm/system_gesture_event_filter.cc
@@ -79,7 +79,8 @@ Widget* CreateAffordanceWidget() {
   params.transparent = true;
   widget->Init(params);
   widget->SetOpacity(0xFF);
-  widget->GetNativeWindow()->SetParent(ash::Shell::GetInstance()->GetContainer(
+  widget->GetNativeWindow()->SetParent(ash::Shell::GetContainer(
+      ash::Shell::GetPrimaryRootWindow(),
       ash::internal::kShellWindowId_OverlayContainer));
   ash::SetWindowVisibilityAnimationTransition(widget->GetNativeView(),
       ash::ANIMATE_HIDE);
diff --git a/ash/wm/system_modal_container_layout_manager_unittest.cc b/ash/wm/system_modal_container_layout_manager_unittest.cc
index 616cd1c..3eaa467 100644
--- a/ash/wm/system_modal_container_layout_manager_unittest.cc
+++ b/ash/wm/system_modal_container_layout_manager_unittest.cc
@@ -25,12 +25,14 @@ namespace test {
 namespace {
 
 aura::Window* GetModalContainer() {
-  return Shell::GetInstance()->GetContainer(
+  return Shell::GetContainer(
+      Shell::GetPrimaryRootWindow(),
       ash::internal::kShellWindowId_SystemModalContainer);
 }
 
 aura::Window* GetDefaultContainer() {
-  return Shell::GetInstance()->GetContainer(
+  return Shell::GetContainer(
+      Shell::GetPrimaryRootWindow(),
       ash::internal::kShellWindowId_DefaultContainer);
 }
 
@@ -271,7 +273,8 @@ TEST_F(SystemModalContainerLayoutManagerTest, EventFocusContainers) {
   Shell::GetInstance()->delegate()->LockScreen();
   EventTestWindow* lock_delegate = new EventTestWindow(false);
   scoped_ptr<aura::Window> lock(lock_delegate->OpenTestWindow(
-      Shell::GetInstance()->GetContainer(
+      Shell::GetContainer(
+          Shell::GetPrimaryRootWindow(),
           ash::internal::kShellWindowId_LockScreenContainer)));
   EXPECT_TRUE(wm::IsActiveWindow(lock.get()));
   e1.ClickLeftButton();
@@ -297,7 +300,8 @@ TEST_F(SystemModalContainerLayoutManagerTest, EventFocusContainers) {
 // is hidden.
 TEST_F(SystemModalContainerLayoutManagerTest, ShowModalWhileHidden) {
   // Hide the lock screen.
-  Shell::GetInstance()->GetContainer(
+  Shell::GetContainer(
+      Shell::GetPrimaryRootWindow(),
       internal::kShellWindowId_SystemModalContainer)->layer()->SetOpacity(0);
 
   // Create a modal window.
diff --git a/ash/wm/window_animations_unittest.cc b/ash/wm/window_animations_unittest.cc
index 9628db2..bf51c1e 100644
--- a/ash/wm/window_animations_unittest.cc
+++ b/ash/wm/window_animations_unittest.cc
@@ -23,7 +23,8 @@ typedef ash::test::AshTestBase WindowAnimationsTest;
 
 TEST_F(WindowAnimationsTest, HideShow) {
   aura::Window* default_container =
-      ash::Shell::GetInstance()->GetContainer(
+      ash::Shell::GetContainer(
+          Shell::GetPrimaryRootWindow(),
           internal::kShellWindowId_DefaultContainer);
   scoped_ptr<aura::Window> window(
       aura::test::CreateTestWindowWithId(0, default_container));
@@ -60,7 +61,8 @@ TEST_F(WindowAnimationsTest, HideShow) {
 
 TEST_F(WindowAnimationsTest, ShowHide) {
   aura::Window* default_container =
-      ash::Shell::GetInstance()->GetContainer(
+      ash::Shell::GetContainer(
+          Shell::GetPrimaryRootWindow(),
           internal::kShellWindowId_DefaultContainer);
   scoped_ptr<aura::Window> window(
       aura::test::CreateTestWindowWithId(0, default_container));
@@ -97,7 +99,8 @@ TEST_F(WindowAnimationsTest, ShowHide) {
 
 TEST_F(WindowAnimationsTest, LayerTargetVisibility) {
   aura::Window* default_container =
-      ash::Shell::GetInstance()->GetContainer(
+      ash::Shell::GetContainer(
+          Shell::GetPrimaryRootWindow(),
           internal::kShellWindowId_DefaultContainer);
   scoped_ptr<aura::Window> window(
       aura::test::CreateTestWindowWithId(0, default_container));
@@ -113,7 +116,8 @@ TEST_F(WindowAnimationsTest, LayerTargetVisibility) {
 
 TEST_F(WindowAnimationsTest, CrossFadeToBounds) {
   Window* default_container =
-      ash::Shell::GetInstance()->GetContainer(
+      ash::Shell::GetContainer(
+          Shell::GetPrimaryRootWindow(),
           internal::kShellWindowId_DefaultContainer);
   scoped_ptr<Window> window(
       aura::test::CreateTestWindowWithId(0, default_container));
diff --git a/ash/wm/window_cycle_controller.cc b/ash/wm/window_cycle_controller.cc
index a79ed88..0345c4b 100644
--- a/ash/wm/window_cycle_controller.cc
+++ b/ash/wm/window_cycle_controller.cc
@@ -127,8 +127,11 @@ void WindowCycleController::AltKeyReleased() {
 
 // static
 std::vector<aura::Window*> WindowCycleController::BuildWindowList() {
-  aura::Window* default_container = ash::Shell::GetInstance()->GetContainer(
-    ash::internal::kShellWindowId_DefaultContainer);
+  // TODO(oshima): Figure out how this should work with multiple root
+  // windows. Just use active root window for now.
+  aura::Window* default_container = Shell::GetContainer(
+      Shell::GetActiveRootWindow(),
+      internal::kShellWindowId_DefaultContainer);
   WindowCycleList::WindowList windows = default_container->children();
   // Removes unfocusable windows.
   WindowCycleList::WindowList::iterator last =
diff --git a/ash/wm/window_cycle_controller_unittest.cc b/ash/wm/window_cycle_controller_unittest.cc
index 006d766..79b6dc8 100644
--- a/ash/wm/window_cycle_controller_unittest.cc
+++ b/ash/wm/window_cycle_controller_unittest.cc
@@ -36,7 +36,8 @@ TEST_F(WindowCycleControllerTest, HandleCycleWindowBaseCases) {
 
   // Create a single test window.
   Window* default_container =
-      ash::Shell::GetInstance()->GetContainer(
+      ash::Shell::GetContainer(
+          Shell::GetPrimaryRootWindow(),
           internal::kShellWindowId_DefaultContainer);
   scoped_ptr<Window> window0(CreateTestWindowWithId(0, default_container));
   wm::ActivateWindow(window0.get());
@@ -55,7 +56,8 @@ TEST_F(WindowCycleControllerTest, SingleWindowNotActive) {
 
   // Create a single test window.
   Window* default_container =
-      ash::Shell::GetInstance()->GetContainer(
+      ash::Shell::GetContainer(
+          Shell::GetPrimaryRootWindow(),
           internal::kShellWindowId_DefaultContainer);
   scoped_ptr<Window> window0(CreateTestWindowWithId(0, default_container));
   wm::ActivateWindow(window0.get());
@@ -78,7 +80,8 @@ TEST_F(WindowCycleControllerTest, HandleCycleWindow) {
   // Set up several windows to use to test cycling.  Create them in reverse
   // order so they are stacked 0 over 1 over 2.
   Window* default_container =
-      Shell::GetInstance()->GetContainer(
+      Shell::GetContainer(
+          Shell::GetPrimaryRootWindow(),
           internal::kShellWindowId_DefaultContainer);
   scoped_ptr<Window> window2(CreateTestWindowWithId(2, default_container));
   scoped_ptr<Window> window1(CreateTestWindowWithId(1, default_container));
@@ -164,7 +167,8 @@ TEST_F(WindowCycleControllerTest, HandleCycleWindow) {
 
   // When a modal window is active, cycling window does not take effect.
   aura::Window* modal_container =
-      ash::Shell::GetInstance()->GetContainer(
+      ash::Shell::GetContainer(
+          Shell::GetPrimaryRootWindow(),
           internal::kShellWindowId_SystemModalContainer);
   scoped_ptr<Window> modal_window(
       CreateTestWindowWithId(-2, modal_container));
@@ -186,7 +190,8 @@ TEST_F(WindowCycleControllerTest, HandleCycleWindow) {
 TEST_F(WindowCycleControllerTest, MaximizedWindow) {
   // Create a couple of test windows.
   Window* default_container =
-      ash::Shell::GetInstance()->GetContainer(
+      ash::Shell::GetContainer(
+          Shell::GetPrimaryRootWindow(),
           internal::kShellWindowId_DefaultContainer);
   scoped_ptr<Window> window0(CreateTestWindowWithId(0, default_container));
   scoped_ptr<Window> window1(CreateTestWindowWithId(1, default_container));
@@ -210,7 +215,8 @@ TEST_F(WindowCycleControllerTest, MaximizedWindow) {
 TEST_F(WindowCycleControllerTest, Minimized) {
   // Create a couple of test windows.
   Window* default_container =
-      ash::Shell::GetInstance()->GetContainer(
+      Shell::GetContainer(
+          Shell::GetPrimaryRootWindow(),
           internal::kShellWindowId_DefaultContainer);
   scoped_ptr<Window> window0(CreateTestWindowWithId(0, default_container));
   scoped_ptr<Window> window1(CreateTestWindowWithId(1, default_container));
diff --git a/ash/wm/window_properties.cc b/ash/wm/window_properties.cc
index 4b2b80a..7f15c5b 100644
--- a/ash/wm/window_properties.cc
+++ b/ash/wm/window_properties.cc
@@ -4,19 +4,23 @@
 
 #include "ash/wm/window_properties.h"
 
+#include "ash/wm/always_on_top_controller.h"
 #include "ash/wm/shadow_types.h"
 #include "ui/aura/window_property.h"
 #include "ui/ui_controls/ui_controls_aura.h"
 
 // Property type for bool and ui::WindowShowState are
 // defined in aura.
+DECLARE_WINDOW_PROPERTY_TYPE(ash::internal::AlwaysOnTopController*);
 DECLARE_WINDOW_PROPERTY_TYPE(ash::internal::ShadowType);
 DECLARE_WINDOW_PROPERTY_TYPE(ash::WindowPersistsAcrossAllWorkspacesType)
 DECLARE_WINDOW_PROPERTY_TYPE(ui_controls::UIControlsAura*)
 
 namespace ash {
 namespace internal {
-
+DEFINE_OWNED_WINDOW_PROPERTY_KEY(ash::internal::AlwaysOnTopController,
+                                 kAlwaysOnTopControllerKey,
+                                 NULL);
 DEFINE_WINDOW_PROPERTY_KEY(
     bool, kChildWindowVisibilityChangesAnimatedKey, false);
 DEFINE_WINDOW_PROPERTY_KEY(
diff --git a/ash/wm/window_properties.h b/ash/wm/window_properties.h
index 760bcd4..88c1b70 100644
--- a/ash/wm/window_properties.h
+++ b/ash/wm/window_properties.h
@@ -17,11 +17,17 @@ class UIControlsAura;
 
 namespace ash {
 namespace internal {
+class AlwaysOnTopController;
 
 // Shell-specific window property keys.
 
 // Alphabetical sort.
 
+// A Key to store AlwaysOnTopController per RootWindow. The value is
+// owned by the RootWindow.
+extern const aura::WindowProperty<internal::AlwaysOnTopController*>* const
+    kAlwaysOnTopControllerKey;
+
 // Property set on all windows whose child windows' visibility changes are
 // animated.
 extern const aura::WindowProperty<bool>* const
diff --git a/ash/wm/workspace/multi_window_resize_controller.cc b/ash/wm/workspace/multi_window_resize_controller.cc
index 9ff22ea..61d140d 100644
--- a/ash/wm/workspace/multi_window_resize_controller.cc
+++ b/ash/wm/workspace/multi_window_resize_controller.cc
@@ -356,8 +356,9 @@ void MultiWindowResizeController::ShowNow() {
   views::Widget::InitParams params(views::Widget::InitParams::TYPE_POPUP);
   params.transparent = true;
   params.ownership = views::Widget::InitParams::WIDGET_OWNS_NATIVE_WIDGET;
-  params.parent = Shell::GetInstance()->GetContainer(
-      ash::internal::kShellWindowId_AlwaysOnTopContainer);
+  params.parent = Shell::GetContainer(
+      Shell::GetActiveRootWindow(),
+      internal::kShellWindowId_AlwaysOnTopContainer);
   params.can_activate = false;
   ResizeView* view = new ResizeView(this, windows_.direction);
   params.delegate = new views::WidgetDelegateView;
diff --git a/ash/wm/workspace/phantom_window_controller.cc b/ash/wm/workspace/phantom_window_controller.cc
index 8c60765..ec535ec 100644
--- a/ash/wm/workspace/phantom_window_controller.cc
+++ b/ash/wm/workspace/phantom_window_controller.cc
@@ -125,8 +125,9 @@ void PhantomWindowController::CreatePhantomWidget(const gfx::Rect& bounds) {
   // PhantomWindowController is used by FrameMaximizeButton to highlight the
   // launcher button. Put the phantom in the same window as the launcher so that
   // the phantom is visible.
-  params.parent =
-      Shell::GetInstance()->GetContainer(kShellWindowId_LauncherContainer);
+  params.parent = Shell::GetContainer(
+      Shell::GetActiveRootWindow(),
+      kShellWindowId_LauncherContainer);
   params.can_activate = false;
   params.keep_on_top = true;
   phantom_widget_->set_focus_on_creation(false);
diff --git a/ash/wm/workspace/workspace_manager_unittest.cc b/ash/wm/workspace/workspace_manager_unittest.cc
index b311825..22e20f2 100644
--- a/ash/wm/workspace/workspace_manager_unittest.cc
+++ b/ash/wm/workspace/workspace_manager_unittest.cc
@@ -51,7 +51,9 @@ class WorkspaceManagerTest : public test::AshTestBase {
   }
 
   aura::Window* GetViewport() {
-    return Shell::GetInstance()->GetContainer(kShellWindowId_DefaultContainer);
+    return Shell::GetContainer(
+        Shell::GetPrimaryRootWindow(),
+        kShellWindowId_DefaultContainer);
   }
 
   const std::vector<Workspace*>& workspaces() const {
diff --git a/chrome/browser/chromeos/login/base_login_display_host.cc b/chrome/browser/chromeos/login/base_login_display_host.cc
index aa7de0e..1d88a1f 100644
--- a/chrome/browser/chromeos/login/base_login_display_host.cc
+++ b/chrome/browser/chromeos/login/base_login_display_host.cc
@@ -292,7 +292,8 @@ void BaseLoginDisplayHost::ShutdownDisplayHost(bool post_quit_task) {
 }
 
 void BaseLoginDisplayHost::StartAnimation() {
-  if (ash::Shell::GetInstance()->GetContainer(
+  if (ash::Shell::GetContainer(
+          ash::Shell::GetPrimaryRootWindow(),
           ash::internal::kShellWindowId_DesktopBackgroundContainer)->
           children().empty()) {
     // If there is no background window, don't perform any animation on the
@@ -319,7 +320,8 @@ void BaseLoginDisplayHost::StartAnimation() {
   // Background animation.
   if (do_background_animation) {
     ui::Layer* background_layer =
-        ash::Shell::GetInstance()->GetContainer(
+        ash::Shell::GetContainer(
+            ash::Shell::GetPrimaryRootWindow(),
             ash::internal::kShellWindowId_DesktopBackgroundContainer)->
                 layer();
 
@@ -350,8 +352,9 @@ void BaseLoginDisplayHost::StartAnimation() {
   // Browser windows layer opacity and transform animation.
   if (do_browser_transform_animation || do_browser_opacity_animation) {
     ui::Layer* default_container_layer =
-        ash::Shell::GetInstance()->GetContainer(
-              ash::internal::kShellWindowId_DefaultContainer)->layer();
+        ash::Shell::GetContainer(
+            ash::Shell::GetPrimaryRootWindow(),
+            ash::internal::kShellWindowId_DefaultContainer)->layer();
 
     ui::LayerAnimationElement::AnimatableProperties browser_pause_properties;
 
diff --git a/chrome/browser/chromeos/login/lock_window_aura.cc b/chrome/browser/chromeos/login/lock_window_aura.cc
index 05da9c3..90b4115 100644
--- a/chrome/browser/chromeos/login/lock_window_aura.cc
+++ b/chrome/browser/chromeos/login/lock_window_aura.cc
@@ -42,10 +42,10 @@ void LockWindowAura::Init() {
   views::Widget::InitParams params(
       views::Widget::InitParams::TYPE_WINDOW_FRAMELESS);
   params.show_state = ui::SHOW_STATE_FULLSCREEN;
-  // TODO(flackr): Use a property to specify this container rather than
-  // depending on shell implementation.
+  // TODO(oshima): move the lock screen harness to ash.
   params.parent =
-      ash::Shell::GetInstance()->GetContainer(
+      ash::Shell::GetContainer(
+          ash::Shell::GetPrimaryRootWindow(),
           ash::internal::kShellWindowId_LockScreenContainer);
   views::Widget::Init(params);
   ash::SetWindowVisibilityAnimationTransition(GetNativeView(),
diff --git a/chrome/browser/chromeos/login/simple_web_view_dialog.cc b/chrome/browser/chromeos/login/simple_web_view_dialog.cc
index 085e978..601791a 100644
--- a/chrome/browser/chromeos/login/simple_web_view_dialog.cc
+++ b/chrome/browser/chromeos/login/simple_web_view_dialog.cc
@@ -296,7 +296,8 @@ void SimpleWebViewDialog::ShowPageInfo(content::WebContents* web_contents,
           true,
           this);
   page_info_bubble->set_parent_window(
-      ash::Shell::GetInstance()->GetContainer(
+      ash::Shell::GetContainer(
+          ash::Shell::GetPrimaryRootWindow(),
           ash::internal::kShellWindowId_LockSystemModalContainer));
   CreateViewsBubble(page_info_bubble);
   page_info_bubble->Show();
diff --git a/chrome/browser/chromeos/login/webui_login_display_host.cc b/chrome/browser/chromeos/login/webui_login_display_host.cc
index a51ef3f..ce3943b 100644
--- a/chrome/browser/chromeos/login/webui_login_display_host.cc
+++ b/chrome/browser/chromeos/login/webui_login_display_host.cc
@@ -153,7 +153,8 @@ void WebUILoginDisplayHost::LoadURL(const GURL& url) {
     if (CommandLine::ForCurrentProcess()->HasSwitch(switches::kEnableNewOobe))
       params.transparent = true;
     params.parent =
-        ash::Shell::GetInstance()->GetContainer(
+        ash::Shell::GetContainer(
+            ash::Shell::GetPrimaryRootWindow(),
             ash::internal::kShellWindowId_LockScreenContainer);
 
     login_window_ = new views::Widget;
diff --git a/chrome/browser/chromeos/status/data_promo_notification.cc b/chrome/browser/chromeos/status/data_promo_notification.cc
index b2cf615..2c90d0b 100644
--- a/chrome/browser/chromeos/status/data_promo_notification.cc
+++ b/chrome/browser/chromeos/status/data_promo_notification.cc
@@ -209,7 +209,8 @@ void DataPromoNotification::ShowOptionalMobileDataPromoNotification(
         links);
     mobile_data_bubble_->set_link_listener(listener);
     mobile_data_bubble_->set_parent_window(
-        ash::Shell::GetInstance()->GetContainer(
+        ash::Shell::GetContainer(
+            ash::Shell::GetPrimaryRootWindow(),
             ash::internal::kShellWindowId_SettingBubbleContainer));
     views::BubbleDelegateView::CreateBubble(mobile_data_bubble_);
     mobile_data_bubble_->Show();
diff --git a/chrome/browser/chromeos/system/ash_system_tray_delegate.cc b/chrome/browser/chromeos/system/ash_system_tray_delegate.cc
index c5118c7..dcf5190 100644
--- a/chrome/browser/chromeos/system/ash_system_tray_delegate.cc
+++ b/chrome/browser/chromeos/system/ash_system_tray_delegate.cc
@@ -967,7 +967,8 @@ class SystemTrayDelegate : public ash::SystemTrayDelegate,
   }
 
   virtual gfx::NativeWindow GetNativeWindow() const OVERRIDE {
-    return ash::Shell::GetInstance()->GetContainer(
+    return ash::Shell::GetContainer(
+        ash::Shell::GetPrimaryRootWindow(),
         GetUserLoginStatus() == ash::user::LOGGED_IN_NONE ?
             ash::internal::kShellWindowId_LockSystemModalContainer :
             ash::internal::kShellWindowId_SystemModalContainer);
diff --git a/chrome/browser/pepper_gtalk_message_filter.cc b/chrome/browser/pepper_gtalk_message_filter.cc
index 83d0e58..95a5dba 100644
--- a/chrome/browser/pepper_gtalk_message_filter.cc
+++ b/chrome/browser/pepper_gtalk_message_filter.cc
@@ -48,7 +48,8 @@ void PepperGtalkMessageFilter::OnTalkGetPermission(uint32 plugin_dispatcher_id,
   const string16 message = l10n_util::GetStringUTF16(
       IDS_GTALK_SCREEN_SHARE_DIALOG_MESSAGE);
 
-  aura::Window* parent = ash::Shell::GetInstance()->GetContainer(
+  aura::Window* parent = ash::Shell::GetContainer(
+      ash::Shell::GetActiveRootWindow(),
       ash::internal::kShellWindowId_SystemModalContainer);
   user_response = browser::ShowMessageBox(parent, title, message,
       browser::MESSAGE_BOX_TYPE_QUESTION) == browser::MESSAGE_BOX_RESULT_YES;
diff --git a/chrome/browser/ui/views/ash/screenshot_taker.cc b/chrome/browser/ui/views/ash/screenshot_taker.cc
index 308fa907..e7659ec 100644
--- a/chrome/browser/ui/views/ash/screenshot_taker.cc
+++ b/chrome/browser/ui/views/ash/screenshot_taker.cc
@@ -169,7 +169,8 @@ void ScreenshotTaker::DisplayVisualFeedback(const gfx::Rect& rect) {
   visual_feedback_layer_->SetOpacity(kVisualFeedbackLayerOpacity);
   visual_feedback_layer_->SetBounds(rect);
 
-  ui::Layer* parent = ash::Shell::GetInstance()->GetContainer(
+  ui::Layer* parent = ash::Shell::GetContainer(
+      ash::Shell::GetActiveRootWindow(),
       ash::internal::kShellWindowId_OverlayContainer)->layer();
   parent->Add(visual_feedback_layer_.get());
   visual_feedback_layer_->SetVisible(true);
diff --git a/chrome/browser/ui/views/ash/window_positioner_unittest.cc b/chrome/browser/ui/views/ash/window_positioner_unittest.cc
index 7fb6070..65ad94e 100644
--- a/chrome/browser/ui/views/ash/window_positioner_unittest.cc
+++ b/chrome/browser/ui/views/ash/window_positioner_unittest.cc
@@ -121,9 +121,9 @@ WindowPositionerTest::~WindowPositionerTest() {
 void WindowPositionerTest::SetUp() {
   AshTestBase::SetUp();
   // Create some default dummy windows.
-  aura::Window* default_container =
-      ash::Shell::GetInstance()->GetContainer(
-          ash::internal::kShellWindowId_DefaultContainer);
+  aura::Window* default_container = ash::Shell::GetContainer(
+      ash::Shell::GetPrimaryRootWindow(),
+      ash::internal::kShellWindowId_DefaultContainer);
   window_.reset(aura::test::CreateTestWindowWithId(0, default_container));
   window_->SetBounds(gfx::Rect(16, 32, 640, 320));
   popup_.reset(aura::test::CreateTestWindowWithId(1, default_container));
diff --git a/chrome/browser/ui/window_sizer_ash_unittest.cc b/chrome/browser/ui/window_sizer_ash_unittest.cc
index 2066cd2..92cb5a8 100644
--- a/chrome/browser/ui/window_sizer_ash_unittest.cc
+++ b/chrome/browser/ui/window_sizer_ash_unittest.cc
@@ -604,7 +604,8 @@ TEST_F(WindowSizerTest,
 TEST_F(WindowSizerTestWithBrowser, PlaceNewWindowOverOldWindow) {
   // Create a dummy window.
   aura::Window* default_container =
-      ash::Shell::GetInstance()->GetContainer(
+      ash::Shell::GetContainer(
+          ash::Shell::GetPrimaryRootWindow(),
           ash::internal::kShellWindowId_DefaultContainer);
   scoped_ptr<aura::Window> window(
       aura::test::CreateTestWindowWithId(0, default_container));