Improve existing lock transition - remove black splash.

ash/root_window_controller.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ash/root_window_controller.h"
 
 #include <vector>
 
 #include "ash/desktop_background/desktop_background_widget_controller.h"
 #include "ash/display/display_controller.h"
@@ skipping 114 matching lines @@
 // use the virtual screeen coordinates instead of parent.
 void SetUsesScreenCoordinates(aura::Window* container) {
   container->SetProperty(internal::kUsesScreenCoordinatesKey, true);
 }
 
 // Creates each of the special window containers that holds windows of various
 // types in the shell UI.
 void CreateContainersInRootWindow(aura::RootWindow* root_window) {
   // These containers are just used by PowerButtonController to animate groups
   // of containers simultaneously without messing up the current transformations
-  // on those containers.  These are direct children of the root window; all of
+  // on those containers. These are direct children of the root window; all of
   // the other containers are their children.
+  // Desktop and lock screen background containers are not part of the
+  // lock animation so they are not included in those animate groups.
+  // When screen is locked desktop background is moved to lock screen background
+  // container (moved back on unlock). We want to make sure that there's an
+  // opaque layer occluding the non-lock-screen layers.
+
+  aura::Window* desktop_background_containers = CreateContainer(
+      internal::kShellWindowId_DesktopBackgroundContainer,
+      "DesktopBackgroundContainer",
+      root_window);
+  SetChildWindowVisibilityChangesAnimated(desktop_background_containers);
+
   aura::Window* non_lock_screen_containers = CreateContainer(
       internal::kShellWindowId_NonLockScreenContainersContainer,
       "NonLockScreenContainersContainer",
       root_window);
+
+  aura::Window* lock_background_containers = CreateContainer(
+      internal::kShellWindowId_LockScreenBackgroundContainer,
+      "LockScreenBackgroundContainer",
+      root_window);
+  SetChildWindowVisibilityChangesAnimated(lock_background_containers);
+
   aura::Window* lock_screen_containers = CreateContainer(
       internal::kShellWindowId_LockScreenContainersContainer,
       "LockScreenContainersContainer",
       root_window);
   aura::Window* lock_screen_related_containers = CreateContainer(
       internal::kShellWindowId_LockScreenRelatedContainersContainer,
       "LockScreenRelatedContainersContainer",
       root_window);
 
   CreateContainer(internal::kShellWindowId_UnparentedControlContainer,
                   "UnparentedControlContainer",
                   non_lock_screen_containers);
 
   CreateContainer(internal::kShellWindowId_SystemBackgroundContainer,
                   "SystemBackgroundContainer", non_lock_screen_containers);
 
-  aura::Window* desktop_background_containers = CreateContainer(
-      internal::kShellWindowId_DesktopBackgroundContainer,
-      "DesktopBackgroundContainer",
-      non_lock_screen_containers);
-  SetChildWindowVisibilityChangesAnimated(desktop_background_containers);
-
   aura::Window* default_container = CreateContainer(
       internal::kShellWindowId_DefaultContainer,
       "DefaultContainer",
       non_lock_screen_containers);
   default_container->SetEventFilter(
       new ToplevelWindowEventFilter(default_container));
   SetChildWindowVisibilityChangesAnimated(default_container);
   SetUsesScreenCoordinates(default_container);
 
   aura::Window* always_on_top_container = CreateContainer(
@@ skipping 31 matching lines @@
       new internal::SystemModalContainerLayoutManager(modal_container));
   SetChildWindowVisibilityChangesAnimated(modal_container);
   SetUsesScreenCoordinates(modal_container);
 
   aura::Window* input_method_container = CreateContainer(
       internal::kShellWindowId_InputMethodContainer,
       "InputMethodContainer",
       non_lock_screen_containers);
   SetUsesScreenCoordinates(input_method_container);
 
-  aura::Window* lock_background_containers = CreateContainer(
-      internal::kShellWindowId_LockScreenBackgroundContainer,
-      "LockScreenBackgroundContainer",
-      lock_screen_containers);
-
-  SetChildWindowVisibilityChangesAnimated(lock_background_containers);
-
   // TODO(beng): Figure out if we can make this use
   // SystemModalContainerEventFilter instead of stops_event_propagation.
   aura::Window* lock_container = CreateContainer(
       internal::kShellWindowId_LockScreenContainer,
       "LockScreenContainer",
       lock_screen_containers);
   lock_container->SetLayoutManager(
       new internal::BaseLayoutManager(root_window));
   SetUsesScreenCoordinates(lock_container);
   // TODO(beng): stopsevents
@@ skipping 135 matching lines @@
   // Restore focused or active window if it's still alive.
   if (focused && tracker.Contains(focused) && dst->Contains(focused)) {
     dst->GetFocusManager()->SetFocusedWindow(focused, NULL);
   } else if (active && tracker.Contains(active) && dst->Contains(active)) {
     activation_client->ActivateWindow(active);
   }
 }
 
 }  // namespace internal
 }  // namespace ash