DCHECK that ProfileSyncService is created on the UI thread.

chrome/browser/sync/backend_migrator_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 "chrome/browser/sync/backend_migrator.h"
 
 #include "base/message_loop/message_loop.h"
+#include "base/run_loop.h"
 #include "base/tracked_objects.h"
 #include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/sync/profile_sync_service_mock.h"
 #include "components/sync_driver/data_type_manager_mock.h"
+#include "content/public/test/test_browser_thread_bundle.h"
 #include "sync/internal_api/public/base/model_type_test_util.h"
 #include "sync/internal_api/public/test/test_user_share.h"
 #include "sync/internal_api/public/write_transaction.h"
 #include "sync/protocol/sync.pb.h"
 #include "sync/syncable/directory.h"  // TODO(tim): Remove. Bug 131130.
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 using ::testing::_;
 using ::testing::Eq;
@@ skipping 55 matching lines @@
                          syncer::ModelTypeSet requested_types) {
     if (status == DataTypeManager::OK) {
       DataTypeManager::ConfigureResult result(status, requested_types);
       migrator_->OnConfigureDone(result);
     } else {
       DataTypeManager::ConfigureResult result(
           status,
           requested_types);
       migrator_->OnConfigureDone(result);
     }
-    message_loop_.RunUntilIdle();
+    base::RunLoop run_loop;
+    run_loop.RunUntilIdle();
   }
 
   ProfileSyncService* service() { return &service_; }
   DataTypeManagerMock* manager() { return &manager_; }
   syncer::ModelTypeSet preferred_types() { return preferred_types_; }
   BackendMigrator* migrator() { return migrator_.get(); }
   void RemovePreferredType(syncer::ModelType type) {
     preferred_types_.Remove(type);
     Mock::VerifyAndClear(&service_);
     ON_CALL(service_, GetPreferredDataTypes()).
         WillByDefault(Return(preferred_types_));
   }
 
  private:
   scoped_ptr<SyncSessionSnapshot> snap_;
-  base::MessageLoop message_loop_;
+  content::TestBrowserThreadBundle thread_bundle_;

[maniscalco, 2015/02/18 17:03:00]

nit: can you see about making thread_bundle_ the first data member?  I.e. swap
this line with the one above it.  Generally, you want your message loops to be
the first things created and the last ones destroyed in tests.  Actually, is
snap_ used anywhere?  Maybe you can just delete it. 

[maxbogue, 2015/02/18 19:00:06]

Deleted it and the tests still pass.

   syncer::ModelTypeSet preferred_types_;
   TestingProfile profile_;
   NiceMock<ProfileSyncServiceMock> service_;
   NiceMock<DataTypeManagerMock> manager_;
   syncer::TestUserShare test_user_share_;
   scoped_ptr<BackendMigrator> migrator_;
 };
 
 class MockMigrationObserver : public MigrationObserver {
  public:
@@ skipping 217 matching lines @@
   EXPECT_CALL(
       *manager(),
       PurgeForMigration(_, syncer::CONFIGURE_REASON_MIGRATION)).Times(1);
   migrator()->MigrateTypes(to_migrate);
   SetUnsyncedTypes(syncer::ModelTypeSet());
   SendConfigureDone(DataTypeManager::ABORTED, syncer::ModelTypeSet());
   EXPECT_EQ(BackendMigrator::IDLE, migrator()->state());
 }
 
 };  // namespace browser_sync