DevTools: display reload warning in the responsive design toolbar.

Source/devtools/front_end/overrides.css

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 231 matching lines @@
     width: 10px;
     height: 10px;
     content: "";
     position: relative;
     top: 2px;
     background-position: -202px -107px;
     float: left;
     margin-right: 4px;
 }
 
+@media (-webkit-min-device-pixel-ratio: 1.5) {
+.overrides-view .overrides-footer::before {
+    background-image: url(Images/statusbarButtonGlyphs_2x.png);
+}
+} /* media */
+
 .overrides-view .overrides-footer .warning-icon-small {
     margin-right: 3px;
 }