Tweaks workspace animation code per latest from Nicholas. Additionally

ash/wm/workspace/desktop_background_fade_controller.cc

Index: ash/wm/workspace/desktop_background_fade_controller.cc
diff --git a/ash/wm/workspace/desktop_background_fade_controller.cc b/ash/wm/workspace/desktop_background_fade_controller.cc
new file mode 100644
index 0000000000000000000000000000000000000000..444cd430a1e1ff4253ccc9791d4b548010256e1b
--- /dev/null
+++ b/ash/wm/workspace/desktop_background_fade_controller.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 "ash/wm/workspace/desktop_background_fade_controller.h"
+
+#include "ash/wm/window_animations.h"
+#include "ash/wm/workspace/colored_window_controller.h"
+#include "base/time.h"
+#include "ui/aura/window.h"
+#include "ui/compositor/scoped_layer_animation_settings.h"
+#include "ui/views/widget/widget.h"
+
+namespace ash {
+namespace internal {
+
+DesktopBackgroundFadeController::DesktopBackgroundFadeController(
+    aura::Window* parent,
+    aura::Window* position_above,
+    base::TimeDelta duration,
+    Direction direction) {
+  SkColor start_color, target_color;
+  ui::Tween::Type tween_type;
+  if (direction == FADE_OUT) {
+    start_color = SkColorSetARGB(0, 0, 0, 0);
+    target_color = SK_ColorBLACK;
+    tween_type = ui::Tween::EASE_IN_OUT;
+  } else {
+    start_color = SK_ColorBLACK;
+    target_color = SkColorSetARGB(0, 0, 0, 0);
+    tween_type = ui::Tween::EASE_IN_OUT;
+  }
+
+  window_controller_.reset(
+      new ColoredWindowController(parent, "DesktopFade"));
+
+  // Force the window to be directly on top of the desktop.
+  aura::Window* fade_window = window_controller_->GetWidget()->GetNativeView();
+  parent->StackChildBelow(fade_window, position_above);
+  parent->StackChildAbove(fade_window, position_above);
+  window_controller_->SetColor(start_color);
+  SetWindowVisibilityAnimationTransition(
+      window_controller_->GetWidget()->GetNativeView(), ANIMATE_NONE);
+  window_controller_->GetWidget()->Show();
+  {
+    ui::ScopedLayerAnimationSettings scoped_setter(
+        fade_window->layer()->GetAnimator());
+    scoped_setter.AddObserver(this);
+    scoped_setter.SetTweenType(tween_type);
+    scoped_setter.SetTransitionDuration(duration);
+    window_controller_->SetColor(target_color);
+  }
+}
+
+DesktopBackgroundFadeController::~DesktopBackgroundFadeController() {
+  StopObservingImplicitAnimations();
+}
+
+void DesktopBackgroundFadeController::OnImplicitAnimationsCompleted() {
+  window_controller_.reset();
+}
+
+}  // namespace internal
+}  // namespace ash