Handle extension webrequest API on the IO thread. This speeds up blocking event

chrome/browser/io_thread.cc

 // Copyright (c) 2011 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.
 
 #include "chrome/browser/io_thread.h"
 
 #include <vector>
 
 #include "base/command_line.h"
 #include "base/debug/leak_tracker.h"
@@ skipping 438 matching lines @@
   // Add an observer that will emit network change events to the ChromeNetLog.
   // Assuming NetworkChangeNotifier dispatches in FIFO order, we should be
   // logging the network change before other IO thread consumers respond to it.
   network_change_observer_.reset(
       new LoggingNetworkChangeObserver(net_log_));
 
   globals_->extension_event_router_forwarder =
       extension_event_router_forwarder_;
   globals_->system_network_delegate.reset(new ChromeNetworkDelegate(
       extension_event_router_forwarder_,
+      NULL,
       Profile::kInvalidProfileId,
       &system_enable_referrers_));
   globals_->host_resolver.reset(
       CreateGlobalHostResolver(net_log_));
   globals_->cert_verifier.reset(new net::CertVerifier);
   globals_->dnsrr_resolver.reset(new net::DnsRRResolver);
   globals_->ssl_config_service = GetSSLConfigService();
   globals_->http_auth_handler_factory.reset(CreateDefaultAuthHandlerFactory(
       globals_->host_resolver.get()));
   // For the ProxyScriptFetcher, we use a direct ProxyService.
@@ skipping 222 matching lines @@
   system_params.network_delegate = globals_->system_network_delegate.get();
   system_params.net_log = net_log_;
   globals_->system_http_transaction_factory.reset(
       new net::HttpNetworkLayer(
           new net::HttpNetworkSession(system_params)));
   globals_->system_ftp_transaction_factory.reset(
       new net::FtpNetworkLayer(globals_->host_resolver.get()));
   globals_->system_request_context =
       ConstructSystemRequestContext(globals_, net_log_);
 }