Show the window controls for 3s on entering full-screen mode.

remoting/webapp/window_frame.css

 /* Copyright 2014 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.
  */
 
 html.apps-v2,
 html.apps-v2 body {
   height: 100%;
   width: 100%;
 }
@@ skipping 152 matching lines @@
 
 body.fullscreen .window-controls-hover-target {
   transition-property: opacity, box-shadow, top;
   transition-duration: 0.3s;
   opacity: 0.7;
   top: -33px;
   __MSG_@@bidi_end_edge__: 8px;
 }
 
 body.fullscreen .window-controls-hover-target:hover,
+body.fullscreen .window-controls-hover-target.menu-opened,
 body.fullscreen .window-controls-hover-target.opened,
-body.fullscreen .window-controls-hover-target.menu-opened {
+body.fullscreen .window-controls-hover-target.preview {
   top: -4px;
   opacity: 1.0;
   box-shadow: 1px 1px 10px rgba(0, 0, 0, 0.5);
 }
 
 .fullscreen .window-controls-hover-target.opened .window-controls-stub {
   background-color: #a6a6a6;
 }