Deprecate NonThreadSafe in components/sync in favor of SequenceChecker.

components/sync/engine_impl/js_mutation_event_observer.h

 // Copyright 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 COMPONENTS_SYNC_ENGINE_IMPL_JS_MUTATION_EVENT_OBSERVER_H_
 #define COMPONENTS_SYNC_ENGINE_IMPL_JS_MUTATION_EVENT_OBSERVER_H_
 
 #include <stdint.h>
 
 #include <string>
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
-#include "base/threading/non_thread_safe.h"
+#include "base/sequence_checker.h"
 #include "components/sync/base/weak_handle.h"
 #include "components/sync/engine/sync_manager.h"
 #include "components/sync/syncable/transaction_observer.h"
 
 namespace tracked_objects {
 class Location;
 }  // namespace tracked_objects
 
 namespace syncer {
 
 class JsEventDetails;
 class JsEventHandler;
 
 // Observes all change- and transaction-related events and routes a
 // summarized version to a JsEventHandler.
 class JsMutationEventObserver : public SyncManager::ChangeObserver,
-                                public syncable::TransactionObserver,
-                                public base::NonThreadSafe {
+                                public syncable::TransactionObserver {
  public:
   JsMutationEventObserver();
 
   ~JsMutationEventObserver() override;
 
   base::WeakPtr<JsMutationEventObserver> AsWeakPtr();
 
   void InvalidateWeakPtrs();
 
   void SetJsEventHandler(const WeakHandle<JsEventHandler>& event_handler);
 
   // SyncManager::ChangeObserver implementation.
   void OnChangesApplied(ModelType model_type,
                         int64_t write_transaction_id,
                         const ImmutableChangeRecordList& changes) override;
   void OnChangesComplete(ModelType model_type) override;
 
   // syncable::TransactionObserver implementation.
   void OnTransactionWrite(
       const syncable::ImmutableWriteTransactionInfo& write_transaction_info,
       ModelTypeSet models_with_changes) override;
 
  private:
   WeakHandle<JsEventHandler> event_handler_;
 
   void HandleJsEvent(const tracked_objects::Location& from_here,
                      const std::string& name,
                      const JsEventDetails& details);
 
+  SEQUENCE_CHECKER(sequence_checker_);
+
   base::WeakPtrFactory<JsMutationEventObserver> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(JsMutationEventObserver);
 };
 
 }  // namespace syncer
 
 #endif  // COMPONENTS_SYNC_ENGINE_IMPL_JS_MUTATION_EVENT_OBSERVER_H_