Worker changes to prepare for lock-free shutdown.

sync/internal_api/public/engine/passive_model_worker.cc

Index: sync/internal_api/public/engine/passive_model_worker.cc
diff --git a/sync/internal_api/public/engine/passive_model_worker.cc b/sync/internal_api/public/engine/passive_model_worker.cc
index 50d00cf08176b5b65ce1d9d446bbf66e40784747..73be6e23a38e944033f39375b685e08246dd5448 100644
--- a/sync/internal_api/public/engine/passive_model_worker.cc
+++ b/sync/internal_api/public/engine/passive_model_worker.cc
@@ -8,14 +8,22 @@
 
 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();