Revert of [Cronet] Remove JSON serialization of CronetEngine.Builder

components/cronet/android/chromium_url_request_context.cc

Index: components/cronet/android/chromium_url_request_context.cc
diff --git a/components/cronet/android/chromium_url_request_context.cc b/components/cronet/android/chromium_url_request_context.cc
index 3969ec0cfd99d48b7d797f780afad294b4db1e98..247077d3b36a57bbb54e0b951607b3ac0884322a 100644
--- a/components/cronet/android/chromium_url_request_context.cc
+++ b/components/cronet/android/chromium_url_request_context.cc
@@ -66,11 +66,24 @@
     const JavaParamRef<jobject>& jcaller,
     const JavaParamRef<jstring>& juser_agent,
     jint jlog_level,
-    jlong jconfig) {
+    const JavaParamRef<jstring>& jconfig) {
   std::string user_agent = ConvertJavaStringToUTF8(env, juser_agent);
 
+  std::string config = ConvertJavaStringToUTF8(env, jconfig);
+
+  scoped_ptr<base::Value> config_value = base::JSONReader::Read(config);
+  if (!config_value || !config_value->IsType(base::Value::TYPE_DICTIONARY)) {
+    DLOG(ERROR) << "Bad JSON: " << config;
+    return 0;
+  }
+
   scoped_ptr<URLRequestContextConfig> context_config(
-      reinterpret_cast<URLRequestContextConfig*>(jconfig));
+      new URLRequestContextConfig());
+  base::JSONValueConverter<URLRequestContextConfig> converter;
+  if (!converter.Convert(*config_value, context_config.get())) {
+    DLOG(ERROR) << "Bad Config: " << config_value;
+    return 0;
+  }
 
   // TODO(mef): MinLogLevel is global, shared by all URLRequestContexts.
   // Revisit this if each URLRequestContext would need an individual log level.