Animating docked background in sync with shelf

ash/launcher/launcher_types.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/launcher/launcher_types.h"
 
 namespace ash {
 
 const int kLauncherPreferredSize = 48;
 const int kLauncherBackgroundAlpha = 204;
+const int kTimeToSwitchBackgroundMs = 1000;
 
 LauncherItem::LauncherItem()
     : type(TYPE_UNDEFINED),
       id(0),
       status(STATUS_CLOSED) {
 }
 
 LauncherItem::~LauncherItem() {
 }
 
 }  // namespace ash