[Sync] Replace ClearServerDataCallback with Closure.

components/sync/engine/fake_sync_engine.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/engine/fake_sync_engine.h"
 
 #include "components/sync/engine/activation_context.h"
 #include "components/sync/engine/sync_engine_host.h"
 
 namespace syncer {
@@ skipping 74 matching lines @@
 void FakeSyncEngine::DisableProtocolEventForwarding() {}
 
 void FakeSyncEngine::EnableDirectoryTypeDebugInfoForwarding() {}
 
 void FakeSyncEngine::DisableDirectoryTypeDebugInfoForwarding() {}
 
 void FakeSyncEngine::set_fail_initial_download(bool should_fail) {
   fail_initial_download_ = should_fail;
 }
 
-void FakeSyncEngine::ClearServerData(
-    const SyncManager::ClearServerDataCallback& callback) {
+void FakeSyncEngine::ClearServerData(const base::Closure& callback) {
   callback.Run();
 }
 
 void FakeSyncEngine::OnCookieJarChanged(bool account_mismatch,
                                         bool empty_jar,
                                         const base::Closure& callback) {
   if (!callback.is_null()) {
     callback.Run();
   }
 }
 
 }  // namespace syncer