Make sure the PDF material toolbar gets hidden after loading.

chrome/browser/resources/pdf/pdf.js

 // 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.
 
 'use strict';
 
 /**
  * @return {number} Width of a scrollbar in pixels
  */
 function getScrollbarWidth() {
@@ skipping 429 matching lines @@
       if (this.lastViewportPosition_)
         this.viewport_.position = this.lastViewportPosition_;
       this.paramsParser_.getViewportFromUrlParams(
           this.streamDetails_.originalUrl, this.handleURLParams_.bind(this));
       this.loaded_ = true;
       this.sendScriptingMessage_({
         type: 'documentLoaded'
       });
       while (this.delayedScriptingMessages_.length > 0)
         this.handleScriptingMessage(this.delayedScriptingMessages_.shift());
+
+      if (this.isMaterial_)
+        this.uiManager_.hideUiAfterTimeout();
     }
   },
 
   /**
    * @private
    * An event handler for handling password-submitted events. These are fired
    * when an event is entered into the password screen.
    * @param {Object} event a password-submitted event.
    */
   onPasswordSubmitted_: function(event) {
@@ skipping 339 matching lines @@
    * Each bookmark is an Object containing a:
    * - title
    * - page (optional)
    * - array of children (themselves bookmarks)
    * @type {Array} the top-level bookmarks of the PDF.
    */
   get bookmarks() {
     return this.bookmarks_;
   }
 };