Split HttpNetworkSession::Params into two structs.

ios/chrome/browser/ios_chrome_io_thread.mm

Index: ios/chrome/browser/ios_chrome_io_thread.mm
diff --git a/ios/chrome/browser/ios_chrome_io_thread.mm b/ios/chrome/browser/ios_chrome_io_thread.mm
index 9508c6766973e378ad7091c575461713a3224c2b..e981995140b443735025dac8d77d6842597c69b0 100644
--- a/ios/chrome/browser/ios_chrome_io_thread.mm
+++ b/ios/chrome/browser/ios_chrome_io_thread.mm
@@ -529,6 +529,7 @@ net::URLRequestContext* IOSChromeIOThread::ConstructSystemRequestContext(
     const net::HttpNetworkSession::Params& params,
     net::NetLog* net_log) {
   net::URLRequestContext* context = new SystemURLRequestContext;
+
   context->set_net_log(net_log);
   context->set_host_resolver(globals->host_resolver.get());
   context->set_cert_verifier(globals->cert_verifier.get());
@@ -562,12 +563,12 @@ net::URLRequestContext* IOSChromeIOThread::ConstructSystemRequestContext(
 
   context->set_http_server_properties(globals->http_server_properties.get());
 
-  net::HttpNetworkSession::Params system_params(params);
+  net::HttpNetworkSession::Context session_context;
   net::URLRequestContextBuilder::SetHttpNetworkSessionComponents(
-      context, &system_params);
+      context, &session_context);
 
   globals->system_http_network_session.reset(
-      new net::HttpNetworkSession(system_params));
+      new net::HttpNetworkSession(params, session_context));
   globals->system_http_transaction_factory.reset(
       new net::HttpNetworkLayer(globals->system_http_network_session.get()));
   context->set_http_transaction_factory(