Add download button to MediaDocument on Android.

third_party/WebKit/Source/core/css/html.css

 /*
  * The default style sheet used to render HTML.
  *
  * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 45 matching lines @@
 
 body {
     display: block;
     margin: 8px
 }
 
 body:-webkit-full-page-media {
     background-color: rgb(0, 0, 0)
 }
 
+body:-webkit-full-page-media > div > a {

[esprehn, 2016/03/15 17:33:07]

We can't do this. It adds rules for every <a> in every page. And marks bits on
the ancestors, it means children of all divs that contain anchors also stop
style sharing. You can add a class name or id instead. I think I'd rather you
just put this in a style element in the media document not here.

[qinmin, 2016/03/15 17:52:16]

Done. Moved the style back into MediaDocument

+    display: block;
+    width: 120px;
+    height: 36px;
+    background: #4285F4;
+    font-family: Roboto;
+    font-size: 14px;
+    border-radius: 5px;
+    color: white;
+    font-weight: bold;
+    text-decoration: none;
+    text-transform: uppercase;
+    text-align: center;
+    line-height: 36px;
+    margin: 32px auto 0 auto;
+}
+
+body:-webkit-full-page-media > div {

[esprehn, 2016/03/15 17:33:07]

Ditto, you can't put generic rules or use combinators like this in the UA sheet.

[qinmin, 2016/03/15 17:52:16]

Done.

+    max-height: 100%;
+    max-width: 100%;
+    position: absolute;
+    top: 50%;
+    left: 50%;
+    margin-right: -50%;
+    transform: translate(-50%, -50%);
+}
+
 p {
     display: block;
     -webkit-margin-before: 1__qem;
     -webkit-margin-after: 1__qem;
     -webkit-margin-start: 0;
     -webkit-margin-end: 0;
 }
 
 div {
     display: block
@@ skipping 1040 matching lines @@
 @page {
     /* FIXME: Define the right default values for page properties. */
     size: auto;
     margin: auto;
     padding: 0px;
     border-width: 0px;
 }
 
 /* noscript is handled internally, as it depends on settings. */