Limit PDF helper extension to print preview only

chrome/browser/resources/pdf/browser_api.js

 // Copyright 2015 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';
 
 /**
  * Returns a promise that will resolve to the default zoom factor.
  * @param {!Object} streamInfo The stream object pointing to the data contained
  *     in the PDF.
@@ skipping 160 matching lines @@
     return Promise.all(promises).then(
         function() { return BrowserApi.create(streamInfo, manageZoom); });
   });
 }
 
 /**
  * Creates a BrowserApi instance for an extension not running as a mime handler.
  * @return {Promise<BrowserApi>} A promise to a BrowserApi instance constructed
  *     from the URL.
  */
-function createBrowserApiForStandaloneExtension() {
+function createBrowserApiForPrintPreview() {
   let url = window.location.search.substring(1);
   let streamInfo = {
     streamUrl: url,
     originalUrl: url,
     responseHeaders: {},
     embedded: window.parent != window,
     tabId: -1,
   };
   return new Promise(function(resolve, reject) {
     if (!chrome.tabs) {
       resolve();
       return;
     }
     chrome.tabs.getCurrent(function(tab) {
       streamInfo.tabId = tab.id;
       streamInfo.tabUrl = tab.url;
       resolve();
     });
   }).then(function() { return BrowserApi.create(streamInfo, false); });
 }
 
 /**
  * Returns a promise that will resolve to a BrowserApi instance.
  * @return {Promise<BrowserApi>} A promise to a BrowserApi instance for the
  *     current environment.
  */
 function createBrowserApi() {
-  if (window.location.search)
-    return createBrowserApiForStandaloneExtension();
+  if (location.origin === 'chrome://print') {
+    return createBrowserApiForPrintPreview();
+  }
 
   return createBrowserApiForMimeHandlerView();
 }