Makes the launcher auto-hide for maximized windows. This turned out to

ash/launcher/launcher.h

 // 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 ASH_LAUNCHER_LAUNCHER_H_
 #define ASH_LAUNCHER_LAUNCHER_H_
 #pragma once
 
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
 #include "ash/ash_export.h"
+#include "ui/base/animation/animation_delegate.h"
+#include "ui/base/animation/slide_animation.h"
 
 namespace aura {
 class Window;
 }
 
 namespace gfx {
 class Rect;
 }
 
 namespace views {
 class Widget;
 }
 
 namespace ash {
 
 namespace internal {
 class FocusCycler;
 class LauncherView;
 }
 
 class LauncherDelegate;
 class LauncherModel;
 
-class ASH_EXPORT Launcher {
+class ASH_EXPORT Launcher : public ui::AnimationDelegate {
  public:
+  // How the background can be changed.
+  enum BackgroundChangeSpeed {
+    CHANGE_ANIMATE,
+    CHANGE_IMMEDIATE
+  };
+
   explicit Launcher(aura::Window* window_container);
   ~Launcher();
 
   // Sets the focus cycler.
   void SetFocusCycler(const internal::FocusCycler* focus_cycler);
 
+  // Sets whether the launcher renders a background. Default is false, but is
+  // set to true if a window overlaps the shelf.
+  void SetRendersBackground(bool value, BackgroundChangeSpeed speed);
+
   // Sets the width of the status area.
   void SetStatusWidth(int width);
   int GetStatusWidth();
 
   // Returns the screen bounds of the item for the specified window. If there is
   // no item for the specified window an empty rect is returned.
   gfx::Rect GetScreenBoundsOfItemIconForWindow(aura::Window* window);
   // Only to be called for testing. Retrieves the LauncherView.
   internal::LauncherView* GetLauncherViewForTest();
 
   LauncherDelegate* delegate() { return delegate_.get(); }
 
   LauncherModel* model() { return model_.get(); }
   views::Widget* widget() { return widget_.get(); }
 
   aura::Window* window_container() { return window_container_; }
 
+  // ui::AnimationDelegate overrides:
+  virtual void AnimationProgressed(const ui::Animation* animation) OVERRIDE;
+
  private:
   class DelegateView;
 
   scoped_ptr<LauncherModel> model_;
 
   // Widget hosting the view.
   scoped_ptr<views::Widget> widget_;
 
   aura::Window* window_container_;
 
   // Contents view of the widget. Houses the LauncherView.
   DelegateView* delegate_view_;
 
   // LauncherView used to display icons.
   internal::LauncherView* launcher_view_;
 
   scoped_ptr<LauncherDelegate> delegate_;
 
+  // Used to animate the background.
+  ui::SlideAnimation background_animation_;
+
+  // Whether we render a background.
+  bool renders_background_;
+
+  // Current alpha value of the background.
+  int background_alpha_;
+
   DISALLOW_COPY_AND_ASSIGN(Launcher);
 };
 
 }  // namespace ash
 
 #endif  // ASH_LAUNCHER_LAUNCHER_H_