[Sync] Move thread checking into the ModelSafeWorker interface.

components/sync/driver/glue/sync_backend_host_impl_unittest.cc

 // Copyright 2013 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/driver/glue/sync_backend_host_impl.h"
 
 #include <cstddef>
 #include <utility>
 
 #include "base/files/file_util.h"
@@ skipping 195 matching lines @@
   // Synchronously initializes the backend.
   void InitializeBackend(bool expect_success) {
     EXPECT_CALL(mock_frontend_, OnBackendInitialized(_, _, _, expect_success))
         .WillOnce(InvokeWithoutArgs(QuitMessageLoop));
     SyncBackendHost::HttpPostProviderFactoryGetter
         http_post_provider_factory_getter =
             base::Bind(&NetworkResources::GetHttpPostProviderFactory,
                        base::Unretained(network_resources_.get()), nullptr,
                        base::Bind(&EmptyNetworkTimeUpdate));
     backend_->Initialize(
-        &mock_frontend_, &sync_thread_, base::ThreadTaskRunnerHandle::Get(),
-        base::ThreadTaskRunnerHandle::Get(), WeakHandle<JsEventHandler>(),
+        &mock_frontend_, &sync_thread_, WeakHandle<JsEventHandler>(),
         GURL(std::string()), std::string(), credentials_, true, false,
         base::FilePath(), std::move(fake_manager_factory_),
         MakeWeakHandle(test_unrecoverable_error_handler_.GetWeakPtr()),
         base::Closure(), http_post_provider_factory_getter,
         std::move(saved_nigori_state_));
     base::RunLoop run_loop;
     base::ThreadTaskRunnerHandle::Get()->PostDelayedTask(
         FROM_HERE, run_loop.QuitClosure(), TestTimeouts::action_timeout());
     run_loop.Run();
     // |fake_manager_factory_|'s fake_manager() is set on the sync
@@ skipping 603 matching lines @@
   backend_->StopSyncingForShutdown();
   // Verify that call to DeactivateNonBlockingDataType doesn't assert.
   backend_->DeactivateNonBlockingDataType(AUTOFILL);
   backend_->Shutdown(STOP_SYNC);
   backend_.reset();
 }
 
 }  // namespace
 
 }  // namespace syncer