[Cronet] Remove CronetEngine.Builder JSON serial/deserialization APIs

components/cronet/android/api/src/org/chromium/net/HttpUrlRequestFactoryConfig.java

 // 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.
 
 package org.chromium.net;
 
-import org.json.JSONException;
-
 /**
  * A config for HttpUrlRequestFactory, which allows runtime configuration of
  * HttpUrlRequestFactory.
  * @deprecated Use {@link CronetEngine.Builder} instead.
  */
 @Deprecated
 public class HttpUrlRequestFactoryConfig extends UrlRequestContextConfig {
 
     /**
      * Default config enables SPDY, QUIC, in memory http cache.
      */
     public HttpUrlRequestFactoryConfig() {
         super();
     }
-
-    /**
-     * Create config from json serialized using @toString.
-     */
-    public HttpUrlRequestFactoryConfig(String json) throws JSONException {
-        super(json);
-    }
 }