Changes to print preview layout.

chrome/browser/resources/print_preview/previewarea/preview_area.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. */
 
 #preview-area.preview-area {
   -webkit-box-flex: 1;
   -webkit-user-select: none;
-  background-color: #ccc;
+  background-color: #e6e6e6;
   overflow: hidden;
   position: relative;
 }
 
 .preview-area-plugin-wrapper {
   height: 100%;
   position: absolute;
   width: 100%;
 }
 
@@ skipping 15 matching lines @@
   -webkit-transition-delay: 250ms;
   opacity: 0;
 }
 
 #preview-area .preview-area-overlay-layer {
   -webkit-transition: opacity 200ms linear;
   /* overlayFadeInTransitionDelay = pluginFadeOutTransitionDelay +
    *     pluginFadeOutTransitionDuration = 350ms */
   -webkit-transition-delay: 350ms;
   -webkit-user-select: none;
-  background: #ccc;
+  background: #e6e6e6;
   height: 100%;
   margin: 0;
   opacity: 1;
   position: absolute;
   width: 100%;
   z-index: 1;
 }
 
 #preview-area .preview-area-overlay-layer.invisible {
   /* overlayFadeOutTransitionDuration = 100ms */
@@ skipping 15 matching lines @@
   top: 50%;
 }
 
 #preview-area .preview-area-no-plugin-action-area {
   margin-top: 12px;
 }
 
 #preview-area .preview-area-open-system-dialog-button-throbber {
   vertical-align: middle;
 }