Add the viewer toolbar to the PDF extension

chrome/browser/resources/pdf/elements/viewer-toolbar/viewer-toolbar.css

 /* Copyright 2013 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. */
-body {
-  -webkit-user-select: none;
-  background: none transparent;
-  margin: 0;
+
+:host {
+  bottom: 0;
+  display: block;
+  font-size: 0;
+  opacity: 1;
+  position: fixed;
+  right: 0;
+}
+
+#hover {
+  padding: 20px;
+}
+
+#toolbar {
+  border-radius: 3px;
+  box-shadow: 0 1px 2px gray, 0 3px 3px rgba(0, 0, 0, .2);
   overflow: hidden;
 }
-
-a {
-  display: block;
-  text-decoration: none;
-}
-
-a:active,
-a:hover,
-a:visited {
-  color: inherit;
-  text-decoration: inherit;
-}