Reland "Fix wallpaper fade animation flashing problem"

ash/desktop_background/desktop_background_view.cc

Index: ash/desktop_background/desktop_background_view.cc
diff --git a/ash/desktop_background/desktop_background_view.cc b/ash/desktop_background/desktop_background_view.cc
index 64c8785243826d9056dda3b84686107b50e70219..a4179654c8af184fed919c24fe6bf3dbb77b5eac 100644
--- a/ash/desktop_background/desktop_background_view.cc
+++ b/ash/desktop_background/desktop_background_view.cc
@@ -9,17 +9,48 @@
 #include "ash/ash_export.h"
 #include "ash/shell.h"
 #include "ash/shell_window_ids.h"
+#include "ash/wm/root_window_layout_manager.h"
 #include "ash/wm/window_animations.h"
+#include "base/message_loop.h"
 #include "base/utf_string_conversions.h"
 #include "grit/ui_resources.h"
 #include "ui/aura/root_window.h"
 #include "ui/base/resource/resource_bundle.h"
 #include "ui/gfx/canvas.h"
+#include "ui/gfx/compositor/layer.h"
+#include "ui/gfx/compositor/layer_animation_observer.h"
+#include "ui/gfx/compositor/scoped_layer_animation_settings.h"
 #include "ui/gfx/image/image.h"
 #include "ui/views/widget/widget.h"
 
 namespace ash {
 namespace internal {
+namespace {
+
+class ShowWallpaperAnimationObserver : public ui::ImplicitAnimationObserver {
+ public:
+  explicit ShowWallpaperAnimationObserver(views::Widget* desktop_widget)
+      : desktop_widget_(desktop_widget) {
+  }
+
+  virtual ~ShowWallpaperAnimationObserver() {
+  }
+
+ private:
+  // Overridden from ui::ImplicitAnimationObserver:
+  virtual void OnImplicitAnimationsCompleted() OVERRIDE {
+    internal::RootWindowLayoutManager* root_window_layout =
+      Shell::GetInstance()->root_window_layout();
+    root_window_layout->SetBackgroundWidget(desktop_widget_);
+    MessageLoop::current()->DeleteSoon(FROM_HERE, this);
+  }
+
+  views::Widget* desktop_widget_;
+
+  DISALLOW_COPY_AND_ASSIGN(ShowWallpaperAnimationObserver);
+};
+
+}  // namespace
 
 // For our scaling ratios we need to round positive numbers.
 static int RoundPositive(double x) {
@@ -96,8 +127,7 @@ void DesktopBackgroundView::OnMouseReleased(const views::MouseEvent& event) {
     Shell::GetInstance()->ShowBackgroundMenu(GetWidget(), event.location());
 }
 
-views::Widget* CreateDesktopBackground(const SkBitmap& wallpaper,
-                                       ImageLayout layout) {
+void CreateDesktopBackground(const SkBitmap& wallpaper, ImageLayout layout) {
   views::Widget* desktop_widget = new views::Widget;
   views::Widget::InitParams params(
       views::Widget::InitParams::TYPE_WINDOW_FRAMELESS);
@@ -111,10 +141,16 @@ views::Widget* CreateDesktopBackground(const SkBitmap& wallpaper,
   ash::SetWindowVisibilityAnimationType(
       desktop_widget->GetNativeView(),
       ash::WINDOW_VISIBILITY_ANIMATION_TYPE_FADE);
+  ash::SetWindowVisibilityAnimationTransition(
+      desktop_widget->GetNativeView(),
+      ash::ANIMATE_SHOW);
   desktop_widget->SetBounds(params.parent->bounds());
+  ui::ScopedLayerAnimationSettings settings(desktop_widget->GetNativeView()->
+                                            layer()->GetAnimator());
+  settings.SetPreemptionStrategy(ui::LayerAnimator::ENQUEUE_NEW_ANIMATION);
+  settings.AddObserver(new ShowWallpaperAnimationObserver(desktop_widget));
   desktop_widget->Show();
   desktop_widget->GetNativeView()->SetName("DesktopBackgroundView");
-  return desktop_widget;
 }
 
 }  // namespace internal