PDF: Delete non-material viewer

chrome/browser/resources/pdf/elements/viewer-button/viewer-button.js

-// Copyright 2014 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.
-
-(function() {
-  var dpi = '';
-
-  Polymer({
-    is: 'viewer-button',
-
-    properties: {
-      img: {
-        type: String,
-        observer: 'imgChanged'
-      },
-
-      latchable: {
-        type: Boolean,
-        observer: 'latchableChanged'
-      }
-    },
-
-    created: function() {
-      if (!dpi) {
-        var mql = window.matchMedia('(-webkit-min-device-pixel-ratio: 1.3');
-        dpi = mql.matches ? 'hi' : 'low';
-      }
-    },
-
-    imgChanged: function() {
-      if (this.img) {
-        this.$.icon.style.backgroundImage =
-            'url(' + this.getAttribute('assetpath') + 'img/' + dpi +
-            'DPI/' + this.img + ')';
-      } else {
-        this.$.icon.style.backgroundImage = '';
-      }
-    },
-
-    latchableChanged: function() {
-      if (this.latchable)
-        this.classList.add('latchable');
-      else
-        this.classList.remove('latchable');
-    },
-  });
-})();