Use ScopedTaskEnvironment instead of MessageLoop in components unit tests.

components/sync/engine_impl/sync_encryption_handler_impl_unittest.cc

 // Copyright 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 "components/sync/engine_impl/sync_encryption_handler_impl.h"
 
 #include <stdint.h>
 
 #include <memory>
 
 #include "base/base64.h"
 #include "base/json/json_string_value_serializer.h"
 #include "base/memory/ptr_util.h"
 #include "base/run_loop.h"
+#include "base/test/scoped_task_environment.h"
 #include "base/tracked_objects.h"
 #include "components/sync/base/fake_encryptor.h"
 #include "components/sync/base/model_type_test_util.h"
 #include "components/sync/protocol/nigori_specifics.pb.h"
 #include "components/sync/protocol/sync.pb.h"
 #include "components/sync/syncable/entry.h"
 #include "components/sync/syncable/mutable_entry.h"
 #include "components/sync/syncable/read_node.h"
 #include "components/sync/syncable/read_transaction.h"
 #include "components/sync/syncable/syncable_write_transaction.h"
@@ skipping 325 matching lines @@
     VerifyMigratedNigoriWithTimestamp(migration_time, passphrase_type,
                                       passphrase);
   }
 
  protected:
   TestUserShare test_user_share_;
   FakeEncryptor encryptor_;
   std::unique_ptr<SyncEncryptionHandlerImpl> encryption_handler_;
   StrictMock<SyncEncryptionHandlerObserverMock> observer_;
   TestIdFactory ids_;
-  base::MessageLoop message_loop_;
+  base::test::ScopedTaskEnvironment scoped_task_environment_;
 };
 
 // Verify that the encrypted types are being written to and read from the
 // nigori node properly.
 TEST_F(SyncEncryptionHandlerImplTest, NigoriEncryptionTypes) {
   sync_pb::NigoriSpecifics nigori;
 
   StrictMock<SyncEncryptionHandlerObserverMock> observer2;
   SyncEncryptionHandlerImpl handler2(user_share(), &encryptor_, std::string(),
                                      std::string() /* bootstrap tokens */);
@@ skipping 1926 matching lines @@
   EXPECT_CALL(*observer(),
               OnBootstrapTokenUpdated(_, KEYSTORE_BOOTSTRAP_TOKEN));
   {
     ReadTransaction trans(FROM_HERE, user_share());
     encryption_handler()->SetKeystoreKeys(
         BuildEncryptionKeyProto(kRawKeystoreKey), trans.GetWrappedTrans());
   }
 }
 
 }  // namespace syncer