[Payment Request] window.PaymentRequest must be undefined if PR is disabled

ios/chrome/browser/web/resources/payment_request.js

 // Copyright 2016 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 JavaScript implementation of the Payment Request API. When
  * loaded, installs the API onto the window object. Conforms
  * to https://www.w3.org/TR/payment-request/. Note: This is a work in progress.
  */
 
-goog.provide('__crWeb.paymentRequestManager');
-
 /**
  * This class implements the DOM level 2 EventTarget interface. The
  * Implementation is copied form src/ui/webui/resources/js/cr/event_target.js.
  * This code should be removed once there is a plan to move event_target.js out
  * of WebUI and reuse in iOS.
  * @constructor
  * @implements {EventTarget}
  */
 __gCrWeb.EventTarget =
     function() {
@@ skipping 833 matching lines @@
   }
 
   var message = {
     'command': 'paymentRequest.responseComplete',
     'result': opt_result,
   };
   __gCrWeb.message.invokeOnHost(message);
 
   return __gCrWeb['paymentRequestManager'].responsePromiseResolver.promise;
 };