Paint media element's play button using padding.

third_party/WebKit/Source/core/css/mediaControlsNew.css

 /*
  * Copyright (C) 2009 Apple Inc.  All rights reserved.
  * Copyright (C) 2015 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
@@ skipping 158 matching lines @@
 }
 
 audio::-webkit-media-controls-play-button, video::-webkit-media-controls-play-button {
     -webkit-appearance: media-play-button;
     display: flex;
     flex: none;
     border-sizing: border-box;
     width: 48px;
     height: 48px;
     line-height: 48px;
-    padding: 12px;
+    padding: 16px;
     background-color: initial;
     color: inherit;
 }
 
 audio::-webkit-media-controls-timeline-container, video::-webkit-media-controls-timeline-container {
     -webkit-appearance: media-controls-background;
     display: flex;
     flex-direction: row;
     align-items: center;
     justify-content: flex-end;
@@ skipping 245 matching lines @@
     font-weight: bold;
 }
 
 video::-webkit-media-text-track-container u {
     text-decoration: underline;
 }
 
 video::-webkit-media-text-track-container i {
     font-style: italic;
 }