Limit PDF helper extension to print preview only

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 83 matching lines @@
 function PDFViewer(browserApi) {
   this.browserApi_ = browserApi;
   this.originalUrl_ = this.browserApi_.getStreamInfo().originalUrl;
   this.loadState_ = LoadState.LOADING;
   this.parentWindow_ = null;
   this.parentOrigin_ = null;
   this.isFormFieldFocused_ = false;
 
   this.delayedScriptingMessages_ = [];
 
-  this.isPrintPreview_ = this.originalUrl_.startsWith('chrome://print');
+  this.isPrintPreview_ = location.origin === 'chrome://print';
 
   // Parse open pdf parameters.
   this.paramsParser_ =
       new OpenPDFParamsParser(this.getNamedDestination_.bind(this));
   var toolbarEnabled =
       this.paramsParser_.getUiUrlParams(this.originalUrl_).toolbar &&
       !this.isPrintPreview_;
 
   // The sizer element is placed behind the plugin element to cause scrollbars
   // to be displayed in the window. It is sized according to the document size
@@ skipping 744 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_;
   }
 };