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

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

 // 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.
 
 package org.chromium.net;
 
-import org.json.JSONException;
-
 /**
  * A config for CronetEngine, which allows runtime configuration of
  * CronetEngine.
  * @deprecated use {@link CronetEngine.Builder} instead.
  */
 public class UrlRequestContextConfig extends CronetEngine.Builder {
     public UrlRequestContextConfig() {
         // Context will be passed in later when the ChromiumUrlRequestFactory
         // or ChromiumUrlRequestContext is created.
         super(null);
     }
-
-    public UrlRequestContextConfig(String json) throws JSONException {
-        // Context will be passed in later when the ChromiumUrlRequestFactory
-        // or ChromiumUrlRequestContext is created.
-        super(null, json);
-    }
 }