Remove ModelSafeWorker::work_done_or_stopped().

components/sync/engine/model_safe_worker.h

Index: components/sync/engine/model_safe_worker.h
diff --git a/components/sync/engine/model_safe_worker.h b/components/sync/engine/model_safe_worker.h
index fb34661f69c4ee0602ee87a53bbec51b498712f5..2a075ac80c0fcc1248c91e59774b1b0802df983b 100644
--- a/components/sync/engine/model_safe_worker.h
+++ b/components/sync/engine/model_safe_worker.h
@@ -15,7 +15,6 @@
 #include "base/message_loop/message_loop.h"
 #include "base/single_thread_task_runner.h"
 #include "base/synchronization/lock.h"
-#include "base/synchronization/waitable_event.h"
 #include "components/sync/base/model_type.h"
 #include "components/sync/base/syncer_error.h"
 
@@ -100,8 +99,6 @@ class ModelSafeWorker : public base::RefCountedThreadSafe<ModelSafeWorker>,
   // from a model-safe thread.
   virtual SyncerError DoWorkAndWaitUntilDoneImpl(const WorkCallback& work) = 0;
 
-  base::WaitableEvent* work_done_or_stopped() { return &work_done_or_stopped_; }
-
   // Return true if the worker was stopped. Thread safe.
   bool IsStopped();
 
@@ -120,10 +117,6 @@ class ModelSafeWorker : public base::RefCountedThreadSafe<ModelSafeWorker>,
   base::Lock stopped_lock_;
   bool stopped_;
 
-  // Signal set when work on native thread is finished or when native thread
-  // is to be destroyed so no more work can be done.
-  base::WaitableEvent work_done_or_stopped_;
-
   // Notified when working thread of the worker is to be destroyed.
   WorkerLoopDestructionObserver* observer_;