Add HttpProtocolHandler and convert everything to use it

components/cronet/ios/cronet_environment.cc

Index: components/cronet/ios/cronet_environment.cc
diff --git a/components/cronet/ios/cronet_environment.cc b/components/cronet/ios/cronet_environment.cc
index 00c1fd513373ce48095c3d97b7831bbd594603a1..b34f700429792b35dc764a06cca81014de5eed00 100644
--- a/components/cronet/ios/cronet_environment.cc
+++ b/components/cronet/ios/cronet_environment.cc
@@ -352,9 +352,10 @@ void CronetEnvironment::InitializeOnNetworkThread() {
                          true /* set_up_quic_server_info */);
   main_context_->set_http_transaction_factory(main_cache);
 
-  net::URLRequestJobFactoryImpl* job_factory =
-      new net::URLRequestJobFactoryImpl;
-  main_context_->set_job_factory(job_factory);
+  // TODO(mgersh): Fix this leak too. See https://crbug.com/523858.
+  std::unique_ptr<net::URLRequestJobFactoryImpl> job_factory =
+      net::URLRequestJobFactoryImpl::CreateWithHttpProtocolHandlers();
+  main_context_->set_job_factory(job_factory.release());
   main_context_->set_net_log(net_log_.get());
 }