[Chromoting] Move shared webapp JS files from crd/js -> base/js

remoting/webapp/base/js/credentials_provider.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';
 
 var remoting = remoting || {};
 
 /** @typedef {{clientId: string, sharedSecret: string}} */
 remoting.PairingInfo;
@@ skipping 79 matching lines @@
   if (!this.fetchThirdPartyToken_) {
     Promise.resolve({token: '', secret: ''});
   }
   return new Promise(function(/** Function */ resolve) {
     var onTokenFetched = function(/** string */ token, /** string */ secret) {
       resolve({token: token, secret: secret});
     };
     that.fetchThirdPartyToken_(tokenUrl, hostPublicKey, scope, onTokenFetched);
   });
 };