Only inject ChromeVox classic when necessary.

chrome/browser/resources/chromeos/chromevox/cvox2/background/background.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.
 
 /**
  * @fileoverview The entry point for all ChromeVox2 related code for the
  * background page.
  */
 
 goog.provide('cvox2.Background');
@@ skipping 54 matching lines @@
    * @param {number} tabId
    * @param {Object} changeInfo
    */
   onTabUpdated: function(tabId, changeInfo) {
     chrome.tabs.get(tabId, function(tab) {
       if (!tab.url)
         return;
 
       if (!this.isWhitelisted_(tab.url)) {
         chrome.commands.onCommand.removeListener(this.onGotCommand);
+        cvox.ChromeVox.background.injectChromeVoxIntoTabs([tab], true);
         return;
       }
 
       if (!chrome.commands.onCommand.hasListeners()) {
         chrome.commands.onCommand.addListener(this.onGotCommand);
       }
 
       this.disableClassicChromeVox_(tab.id);
 
       chrome.automation.getTree(this.onGotTree.bind(this));
@@ skipping 129 matching lines @@
   disableClassicChromeVox_: function(tabId) {
     chrome.tabs.executeScript(
           tabId,
           {'code': 'try { window.disableChromeVox(); } catch(e) { }\n',
            'allFrames': true});
   }
 };
 
 /** @type {cvox2.Background} */
 cvox2.global.backgroundObj = new cvox2.Background();