Add missing IWYU message_loop.h includes.

net/http/http_stream_factory_impl_unittest.cc

 // Copyright (c) 2012 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 "net/http/http_stream_factory_impl.h"
 
 #include <stdint.h>
 
 #include <memory>
 #include <string>
 #include <utility>
 #include <vector>
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
+#include "base/message_loop/message_loop.h"
 #include "base/run_loop.h"
 #include "base/test/histogram_tester.h"
 #include "net/base/port_util.h"
 #include "net/base/privacy_mode.h"
 #include "net/base/test_completion_callback.h"
 #include "net/base/test_proxy_delegate.h"
 #include "net/cert/ct_policy_enforcer.h"
 #include "net/cert/mock_cert_verifier.h"
 #include "net/cert/multi_log_ct_verifier.h"
 #include "net/dns/mock_host_resolver.h"
@@ skipping 2675 matching lines @@
       session->GetTransportSocketPool(
           HttpNetworkSession::WEBSOCKET_SOCKET_POOL)));
   EXPECT_EQ(1, GetSocketPoolGroupCount(
       session->GetSSLSocketPool(HttpNetworkSession::WEBSOCKET_SOCKET_POOL)));
   EXPECT_TRUE(waiter.used_proxy_info().is_direct());
 }
 
 }  // namespace
 
 }  // namespace net