Plugin Power Saver: Make posters work right when image is 404 Not Found.

chrome/renderer/resources/plugin_placeholders.css

 /* 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. */
 
+html {
+  height: 100%;
+  width: 100%;
+}
+
 body {
   font-family: sans-serif;
   margin: 0;
   overflow: hidden;
   text-align: center;
   -webkit-user-select: none;
+  height: 100%;
+  width: 100%;
 }
 
 h1 {
   font-size: 10pt;
   font-weight: normal;
   padding: 0pt 10pt;
 <if expr="not is_android and not chromeos">
   visibility: hidden;
 </if>
 }
@@ skipping 49 matching lines @@
   background-image: -webkit-image-set(
       url(../../../ui/resources/default_100_percent/close_2_hover.png) 1x,
       url(../../../ui/resources/default_200_percent/close_2_hover.png) 2x);
 }
 
 #close:active {
   background-image: -webkit-image-set(
       url(../../../ui/resources/default_100_percent/close_2_pressed.png) 1x,
       url(../../../ui/resources/default_200_percent/close_2_pressed.png) 2x);
 }