Implement media cast buttons

Source/core/css/mediaControlsAndroid.css

 /*
  * Copyright (C) 2012 Google Inc.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 55 matching lines @@
 video::-webkit-media-controls-fullscreen-button {
     width: 35px;
     height: 35px;
     line-height: 35px;
 }
 
 audio::-webkit-media-controls-fullscreen-button {
     display: none;
 }
 
+audio::-internal-media-controls-cast-button, video::-internal-media-controls-cast-button {
+    width: 35px;
+    height: 35px;
+    line-height: 35px;
+}
+
 video::-webkit-media-controls-toggle-closed-captions-button {
     width: 35px;
     height: 35px;
     line-height: 35px;
 }