Worker changes to prepare for lock-free shutdown.

sync/test/engine/fake_model_worker.h

Index: sync/test/engine/fake_model_worker.h
diff --git a/sync/test/engine/fake_model_worker.h b/sync/test/engine/fake_model_worker.h
index 7b7bd4b1a0dd48a743e81bea2c074c4c1be8c5bc..be27d2165404d8306a7017ee50f552f5b77d7179 100644
--- a/sync/test/engine/fake_model_worker.h
+++ b/sync/test/engine/fake_model_worker.h
@@ -22,10 +22,13 @@ class FakeModelWorker : public ModelSafeWorker, public base::NonThreadSafe {
   explicit FakeModelWorker(ModelSafeGroup group);
 
   // ModelSafeWorker implementation.
-  virtual SyncerError DoWorkAndWaitUntilDone(
-      const WorkCallback& work) OVERRIDE;
+  virtual void RegisterForLoopDestruction() OVERRIDE;
   virtual ModelSafeGroup GetModelSafeGroup() OVERRIDE;
 
+ protected:
+  virtual SyncerError DoWorkAndWaitUntilDoneImpl(
+      const WorkCallback& work, base::WaitableEvent* done) OVERRIDE;
+
  private:
   virtual ~FakeModelWorker();