PDF: Handle the space bar key like page down.

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';
 
 <include src="../../../../ui/webui/resources/js/util.js">
 <include src="pdf_scripting_api.js">
 <include src="viewport.js">
 
@@ skipping 158 matching lines @@
         // Go to the previous page if we are fit-to-page.
         if (this.viewport_.fittingType == Viewport.FittingType.FIT_TO_PAGE) {
           this.viewport_.goToPage(this.viewport_.getMostVisiblePage() - 1);
           // Since we do the movement of the page.
           e.preventDefault();
         } else if (fromScriptingAPI) {
           position.y -= this.viewport.size.height;
           this.viewport.position = position;
         }
         return;
+      case 32:  // Space key.
       case 34:  // Page down key.
         // Go to the next page if we are fit-to-page.
         if (this.viewport_.fittingType == Viewport.FittingType.FIT_TO_PAGE) {
           this.viewport_.goToPage(this.viewport_.getMostVisiblePage() + 1);
           // Since we do the movement of the page.
           e.preventDefault();
         } else if (fromScriptingAPI) {
           position.y += this.viewport.size.height;
           this.viewport.position = position;
         }
@@ skipping 337 matching lines @@
 
   /**
    * @type {Viewport} the viewport of the PDF viewer.
    */
   get viewport() {
     return this.viewport_;
   }
 };
 
 var viewer = new PDFViewer();