Deprecate NonThreadSafe in components/sync in favor of SequenceChecker.

components/sync/engine/attachments/attachment_store_frontend.h

 // Copyright 2015 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 COMPONENTS_SYNC_ENGINE_ATTACHMENTS_ATTACHMENT_STORE_FRONTEND_H_
 #define COMPONENTS_SYNC_ENGINE_ATTACHMENTS_ATTACHMENT_STORE_FRONTEND_H_
 
 #include <memory>
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
-#include "base/threading/non_thread_safe.h"
+#include "base/sequence_checker.h"
 #include "components/sync/model/attachments/attachment_store.h"
 
 namespace base {
 class SequencedTaskRunner;
 }  // namespace base
 
 namespace syncer {
 
 class AttachmentStoreBackend;
 
 // AttachmentStoreFrontend is helper to post AttachmentStore calls to backend on
 // different thread. Backend is expected to know on which thread to post
 // callbacks with results.
 // AttachmentStoreFrontend takes ownership of backend. Backend is deleted on
 // backend thread.
 // AttachmentStoreFrontend is not thread safe, it should only be accessed from
 // model thread.
 // Method signatures of AttachmentStoreFrontend match exactly methods of
 // AttachmentStoreBackend.
 class AttachmentStoreFrontend
-    : public base::RefCounted<AttachmentStoreFrontend>,
-      public base::NonThreadSafe {
+    : public base::RefCounted<AttachmentStoreFrontend> {
  public:
   AttachmentStoreFrontend(
       std::unique_ptr<AttachmentStoreBackend> backend,
       const scoped_refptr<base::SequencedTaskRunner>& backend_task_runner);
 
   void Init(const AttachmentStore::InitCallback& callback);
 
   void Read(AttachmentStore::Component component,
             const AttachmentIdList& ids,
             const AttachmentStore::ReadCallback& callback);
@@ skipping 14 matching lines @@
   void ReadMetadata(AttachmentStore::Component component,
                     const AttachmentStore::ReadMetadataCallback& callback);
 
  private:
   friend class base::RefCounted<AttachmentStoreFrontend>;
   virtual ~AttachmentStoreFrontend();
 
   std::unique_ptr<AttachmentStoreBackend> backend_;
   scoped_refptr<base::SequencedTaskRunner> backend_task_runner_;
 
+  SEQUENCE_CHECKER(sequence_checker_);
+
   DISALLOW_COPY_AND_ASSIGN(AttachmentStoreFrontend);
 };
 
 }  // namespace syncer
 
 #endif  // COMPONENTS_SYNC_ENGINE_ATTACHMENTS_ATTACHMENT_STORE_FRONTEND_H_