Worker changes to prepare for lock-free shutdown.

sync/internal_api/public/engine/passive_model_worker.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 "sync/internal_api/public/engine/passive_model_worker.h"
 
 #include "base/message_loop.h"
 
 namespace syncer {
 
-PassiveModelWorker::PassiveModelWorker(const base::MessageLoop* sync_loop)
-    : sync_loop_(sync_loop) {}
+PassiveModelWorker::PassiveModelWorker(const base::MessageLoop* sync_loop,
+                                       WorkerLoopDestructionObserver* observer)
+    : ModelSafeWorker(observer),
+      sync_loop_(sync_loop) {
+}
 
 PassiveModelWorker::~PassiveModelWorker() {
 }
 
-SyncerError PassiveModelWorker::DoWorkAndWaitUntilDone(
-    const WorkCallback& work) {
+void PassiveModelWorker::RegisterForLoopDestruction() {
+  NOTREACHED();
+}
+
+SyncerError PassiveModelWorker::DoWorkAndWaitUntilDoneImpl(
+    const WorkCallback& work,
+    base::WaitableEvent* done) {
   DCHECK_EQ(base::MessageLoop::current(), sync_loop_);
   // Simply do the work on the current thread.
   return work.Run();
 }
 
 ModelSafeGroup PassiveModelWorker::GetModelSafeGroup() {
   return GROUP_PASSIVE;
 }
 
 }  // namespace syncer