Instantiate ScopedTaskEnvironment in net unittests.

net/test/net_test_suite.h

 // 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.
 
 #ifndef NET_TEST_NET_TEST_SUITE_H_
 #define NET_TEST_NET_TEST_SUITE_H_
 
 #include <memory>
 
 #include "base/memory/ref_counted.h"
 #include "base/test/test_suite.h"
 #include "build/build_config.h"
 #include "net/dns/mock_host_resolver.h"
 
 namespace base {
-class MessageLoop;
+namespace test {
+class ScopedTaskEnvironment;
+}
 }
 
 namespace net {
 class NetworkChangeNotifier;
 }
 
 class NetTestSuite : public base::TestSuite {
  public:
   NetTestSuite(int argc, char** argv);
   ~NetTestSuite() override;
 
   void Initialize() override;
 
   void Shutdown() override;
 
+  // Returns the base::test::ScopedTaskEnvironment initialized by the current
+  // NetTestSuite.
+  static base::test::ScopedTaskEnvironment* GetScopedTaskEnvironment();
+
  protected:
   // Called from within Initialize(), but separate so that derived classes
   // can initialize the NetTestSuite instance only and not
   // TestSuite::Initialize().  TestSuite::Initialize() performs some global
   // initialization that can only be done once.
   void InitializeTestThread();
 
   // Same as above, except it does not create a mock
   // NetworkChangeNotifier.  Use this if your test needs to create and
   // manage its own mock NetworkChangeNotifier, or if your test uses
   // the production NetworkChangeNotifier.
   void InitializeTestThreadNoNetworkChangeNotifier();
 
  private:
   std::unique_ptr<net::NetworkChangeNotifier> network_change_notifier_;
-  std::unique_ptr<base::MessageLoop> message_loop_;
+  std::unique_ptr<base::test::ScopedTaskEnvironment> scoped_task_environment_;
   scoped_refptr<net::RuleBasedHostResolverProc> host_resolver_proc_;
   net::ScopedDefaultHostResolverProc scoped_host_resolver_proc_;
 };
 
 #endif  // NET_TEST_NET_TEST_SUITE_H_