ui/file_manager/video_player/js/cast/cast_extension_discoverer.js

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 /**
   6  * Discover the ID of installed cast extension.
   7  * @constructor
   8  * @struct
   9  */
  10 function CastExtensionDiscoverer() {}
  11
  12 /**
  13  * Tentatice IDs to try.
  14  * @type {!Array<string>}
  15  * @const
  16  */
  17 CastExtensionDiscoverer.CAST_EXTENSION_IDS = [
  18   'boadgeojelhgndaghljhdicfkmllpafd', // release
  19   'dliochdbjfkdbacpmhlcpmleaejidimm', // beta
  20   'hfaagokkkhdbgiakmmlclaapfelnkoah',
  21   'fmfcbgogabcbclcofgocippekhfcmgfj',
  22   'enhhojjnijigcajfphajepfemndkmdlo'
  23 ];
  24
  25 /**
  26  * @param {function(?string)} callback Callback called with the extension ID.
  27  *     The ID may be null if extension is not found.
  28  */
  29 CastExtensionDiscoverer.findInstalledExtension = function(callback) {
  30   CastExtensionDiscoverer.findInstalledExtensionHelper_(0, callback);
  31 };
  32
  33 /**
  34  * @param {number} index Current index which is tried to check.
  35  * @param {function(?string)} callback Callback function which will be called
  36  *     the extension is found.
  37  * @private
  38  */
  39 CastExtensionDiscoverer.findInstalledExtensionHelper_ = function(index,
  40     callback) {
  41   if (index === CastExtensionDiscoverer.CAST_EXTENSION_IDS.length) {
  42     // no extension found.
  43     callback(null);
  44     return;
  45   }
  46
  47   CastExtensionDiscoverer.isExtensionInstalled_(
  48       CastExtensionDiscoverer.CAST_EXTENSION_IDS[index],
  49       function(installed) {
  50         if (installed) {
  51           callback(CastExtensionDiscoverer.CAST_EXTENSION_IDS[index]);
  52         } else {
  53           CastExtensionDiscoverer.findInstalledExtensionHelper_(index + 1,
  54                                                                 callback);
  55         }
  56       });
  57 };
  58
  59 /**
  60  * The result will be notified on |callback|. True if installed, false not.
  61  * @param {string} extensionId Id to be checked.
  62  * @param {function(boolean)} callback Callback to notify the result.
  63  * @private
  64  */
  65 CastExtensionDiscoverer.isExtensionInstalled_ =
  66     function(extensionId, callback) {
  67
  68   var xhr = new XMLHttpRequest();
  69   var url = 'chrome-extension://' + extensionId + '/cast_sender.js';
  70   xhr.open('GET', url, true);
  71   xhr.onerror = function() { callback(false); };
  72   /** @param {*} event */
  73   xhr.onreadystatechange = function(event) {
  74     if (xhr.readyState == 4 && xhr.status === 200) {
  75       // Cast extension found.
  76       callback(true);
  77     }
  78   }.wrap(this);
  79   xhr.send();
  80 };