Modify pdf_scripting_api.js to support postMessage using BrowserPlugin

chrome/browser/resources/pdf/main.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.
 
 'use strict';
 
 /**
  * Global PDFViewer object, accessible for testing.
  * @type Object
  */
 var viewer;
 
 /**
  * Entrypoint for starting the PDF viewer. This function obtains the details
  * of the PDF 'stream' (the data that points to the PDF) and constructs a
  * PDFViewer object with it.
  */
 (function main() {
+  viewer = new PDFViewer();
+
   // If the viewer is started from the browser plugin, the view ID will be
   // passed in which identifies the instance of the plugin.
   var params = window.location.search.substring(1).split('=');
   if (params.length == 2 && params[0] == 'id') {
     var viewId = params[1];
 
     // Send a message to the background page to obtain the stream details. It
     // will run the callback function passed in to initialize the viewer.
     chrome.runtime.sendMessage(
         'mhjfbmdgcfjbbpaeojofohoefgiehjai',
         {viewId: viewId},
-        function(streamDetails) { viewer = new PDFViewer(streamDetails); });
+        function(streamDetails) { viewer.init(streamDetails); });
     return;
   }
 
   // The viewer may be started directly by passing in the URL of the PDF to load
   // as the query string. This is used for print preview in particular. The URL
   // of this page will be of the form
   // 'chrome-extension://<extension id>?<pdf url>'. We pull out the <pdf url>
   // part here.
   var url = window.location.search.substring(1);
   var streamDetails = {
     streamUrl: url,
     originalUrl: url,
     responseHeaders: '',
     embedded: window.parent != window,
     tabId: -1
   };
   if (!chrome.tabs) {
-    viewer = new PDFViewer(streamDetails);
+    viewer.init(streamDetails);
     return;
   }
   chrome.tabs.getCurrent(function(tab) {
     if (tab && tab.id != undefined)
       streamDetails.tabId = tab.id;
-    viewer = new PDFViewer(streamDetails);
+    viewer.init(streamDetails);
   });
 })();