[Cronet] Replace setExperimentalQuicConnectionOptions with a more general API

components/cronet/url_request_context_config.h

 // 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.
 
 #ifndef COMPONENTS_CRONET_URL_REQUEST_CONTEXT_CONFIG_H_
 #define COMPONENTS_CRONET_URL_REQUEST_CONTEXT_CONFIG_H_
 
 #include <string>
 
 #include "base/json/json_value_converter.h"
@@ skipping 57 matching lines @@
   int http_cache_max_size;
   // Disable caching for HTTP responses. Other information may be stored in
   // the cache.
   bool load_disable_cache;
   // Storage path for http cache and cookie storage.
   std::string storage_path;
   // User-Agent request header field.
   std::string user_agent;
   // App-provided list of servers that support QUIC.
   ScopedVector<QuicHint> quic_hints;
-  // Comma-separated list of QUIC connection options.
-  std::string quic_connection_options;
+  // Experimental options encoded as a string in a JSON format containing
+  // experiments and their corresponding configuration options. The format
+  // is a JSON object with the name of the experiment as the key, and the
+  // configuration options as the value. An example:
+  //   {"experiment1": {"option1": "option_value1", "option2": "option_value2",
+  //    ...}, "experiment2: {"option3", "option_value3", ...}, ...}
+  std::string experimental_options;
   // Enable Data Reduction Proxy with authentication key.
   std::string data_reduction_proxy_key;
   std::string data_reduction_primary_proxy;
   std::string data_reduction_fallback_proxy;
   std::string data_reduction_secure_proxy_check_url;
 
   // Certificate verifier for testing.
   scoped_ptr<net::CertVerifier> mock_cert_verifier;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(URLRequestContextConfig);
 };
 
 }  // namespace cronet
 
 #endif  // COMPONENTS_CRONET_URL_REQUEST_CONTEXT_CONFIG_H_