sync: Implement disabling of non blocking types

sync/internal_api/sync_core_proxy_impl.h

 // Copyright 2014 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 SYNC_INTERNAL_API_SYNC_CORE_PROXY_IMPL_H_
 #define SYNC_INTERNAL_API_SYNC_CORE_PROXY_IMPL_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "base/sequenced_task_runner.h"
@@ skipping 22 matching lines @@
   //
   // This may fail under some unusual circumstances, like shutdown.  Due to the
   // nature of WeakPtrs and cross-thread communication, the caller will be
   // unable to distinguish a slow success from failure.
   //
   // Must be called from the thread where the data type lives.
   virtual void ConnectTypeToCore(
       syncer::ModelType type,
       base::WeakPtr<NonBlockingTypeProcessor> type_processor) OVERRIDE;
 
+  // Disables syncing for the given type on the sync thread.
+  virtual void Disconnect(syncer::ModelType type) OVERRIDE;
+
   virtual scoped_ptr<SyncCoreProxy> Clone() const OVERRIDE;
 
  private:
   // A SequencedTaskRunner representing the thread where the SyncCore lives.
   scoped_refptr<base::SequencedTaskRunner> sync_task_runner_;
 
   // The SyncCore this object is wrapping.
   base::WeakPtr<SyncCore> sync_core_;
 };
 
 }  // namespace syncer
 
 #endif  // SYNC_INTERNAL_API_SYNC_CORE_PROXY_IMPL_H_