Worker changes to prepare for lock-free shutdown.

chrome/browser/sync/glue/browser_thread_model_worker.h

 // 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.
 
 #ifndef CHROME_BROWSER_SYNC_GLUE_BROWSER_THREAD_MODEL_WORKER_H_
 #define CHROME_BROWSER_SYNC_GLUE_BROWSER_THREAD_MODEL_WORKER_H_
 
 #include "base/basictypes.h"
 #include "base/callback_forward.h"
 #include "base/compiler_specific.h"
 #include "content/public/browser/browser_thread.h"
 #include "sync/internal_api/public/engine/model_safe_worker.h"
 #include "sync/internal_api/public/util/syncer_error.h"
 
 namespace base {
 class WaitableEvent;
 }
 
 namespace browser_sync {
 
 // A syncer::ModelSafeWorker for models that accept requests from the
 // syncapi that need to be fulfilled on a browser thread, for example
-// autofill on the DB thread.  TODO(sync): Try to generalize other
-// ModelWorkers (e.g. history, etc).
+// autofill on the DB thread.
+// TODO(sync): Try to generalize other ModelWorkers (e.g. history, etc).
 class BrowserThreadModelWorker : public syncer::ModelSafeWorker {
  public:
   BrowserThreadModelWorker(content::BrowserThread::ID thread,
-                           syncer::ModelSafeGroup group);
+                           syncer::ModelSafeGroup group,
+                           syncer::WorkerLoopDestructionObserver* observer);
 
   // syncer::ModelSafeWorker implementation. Called on the sync thread.
-  virtual syncer::SyncerError DoWorkAndWaitUntilDone(
-      const syncer::WorkCallback& work) OVERRIDE;
+  virtual void RegisterForLoopDestruction() OVERRIDE;
   virtual syncer::ModelSafeGroup GetModelSafeGroup() OVERRIDE;
 
  protected:
   virtual ~BrowserThreadModelWorker();
 
+  virtual syncer::SyncerError DoWorkAndWaitUntilDoneImpl(
+      const syncer::WorkCallback& work) OVERRIDE;
+
   // Marked pure virtual so subclasses have to override, but there is
   // an implementation that subclasses should use.  This is so that
   // (subclass)::CallDoWorkAndSignalTask shows up in callstacks.
   virtual void CallDoWorkAndSignalTask(
       const syncer::WorkCallback& work,
       base::WaitableEvent* done,
       syncer::SyncerError* error) = 0;
 
  private:
   content::BrowserThread::ID thread_;
   syncer::ModelSafeGroup group_;
 
   DISALLOW_COPY_AND_ASSIGN(BrowserThreadModelWorker);
 };
 
 // Subclass BrowserThreadModelWorker so that we can distinguish them
 // from stack traces alone.
 
 class DatabaseModelWorker : public BrowserThreadModelWorker {
  public:
-  DatabaseModelWorker();
+  explicit DatabaseModelWorker(syncer::WorkerLoopDestructionObserver* observer);
 
  protected:
   virtual void CallDoWorkAndSignalTask(
       const syncer::WorkCallback& work,
       base::WaitableEvent* done,
       syncer::SyncerError* error) OVERRIDE;
 
  private:
   virtual ~DatabaseModelWorker();
 };
 
 class FileModelWorker : public BrowserThreadModelWorker {
  public:
-  FileModelWorker();
+  explicit FileModelWorker(syncer::WorkerLoopDestructionObserver* observer);
 
  protected:
   virtual void CallDoWorkAndSignalTask(
       const syncer::WorkCallback& work,
       base::WaitableEvent* done,
       syncer::SyncerError* error) OVERRIDE;
 
  private:
   virtual ~FileModelWorker();
 };
 
 }  // namespace browser_sync
 
 #endif  // CHROME_BROWSER_SYNC_GLUE_BROWSER_THREAD_MODEL_WORKER_H_