Revert of Draggable peeking/fullscreen launcher with transparent background.

ash/shell_observer.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_SHELL_OBSERVER_H_
 #define ASH_SHELL_OBSERVER_H_
 
 #include "ash/ash_export.h"
 #include "ash/login_status.h"
 
 namespace aura {
 class Window;
 }
 
 namespace ash {
 
 class ASH_EXPORT ShellObserver {
  public:
-  // Called when the AppList is shown or dismissed.
-  virtual void OnAppListVisibilityChanged(bool shown,
-                                          aura::Window* root_window) {}
-
   // Called when a casting session is started or stopped.
   virtual void OnCastingSessionStartedOrStopped(bool started) {}
 
   // Invoked after a non-primary root window is created.
   virtual void OnRootWindowAdded(aura::Window* root_window) {}
 
   // Invoked after the shelf has been created for |root_window|.
   virtual void OnShelfCreatedForRootWindow(aura::Window* root_window) {}
 
   // Invoked when the shelf alignment in |root_window| is changed.
@@ skipping 40 matching lines @@
   // Called at the end of Shell::Init.
   virtual void OnShellInitialized() {}
 
  protected:
   virtual ~ShellObserver() {}
 };
 
 }  // namespace ash
 
 #endif  // ASH_SHELL_OBSERVER_H_