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      1 // Copyright 2014 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef SYNC_INTERNAL_API_SYNC_CONTEXT_PROXY_IMPL_H_
      6 #define SYNC_INTERNAL_API_SYNC_CONTEXT_PROXY_IMPL_H_
      7 
      8 #include "base/memory/scoped_ptr.h"
      9 #include "base/memory/weak_ptr.h"
     10 #include "base/sequenced_task_runner.h"
     11 #include "sync/base/sync_export.h"
     12 #include "sync/internal_api/public/base/model_type.h"
     13 #include "sync/internal_api/public/sync_context_proxy.h"
     14 
     15 namespace syncer {
     16 
     17 class SyncContext;
     18 class ModelTypeSyncProxyImpl;
     19 struct DataTypeState;
     20 
     21 // Encapsulates a reference to the sync context and the thread it's running on.
     22 // Used by sync's data types to connect with the sync context.
     23 //
     24 // It is expected that this object will be copied to and used on many different
     25 // threads.  It is small and safe to pass by value.
     26 class SYNC_EXPORT_PRIVATE SyncContextProxyImpl : public SyncContextProxy {
     27  public:
     28   SyncContextProxyImpl(
     29       const scoped_refptr<base::SequencedTaskRunner>& sync_task_runner,
     30       const base::WeakPtr<SyncContext>& sync_context);
     31   virtual ~SyncContextProxyImpl();
     32 
     33   // Attempts to connect a non-blocking type to the sync context.
     34   //
     35   // This may fail under some unusual circumstances, like shutdown.  Due to the
     36   // nature of WeakPtrs and cross-thread communication, the caller will be
     37   // unable to distinguish a slow success from failure.
     38   //
     39   // Must be called from the thread where the data type lives.
     40   virtual void ConnectTypeToSync(
     41       syncer::ModelType type,
     42       const DataTypeState& data_type_state,
     43       const UpdateResponseDataList& pending_updates,
     44       const base::WeakPtr<ModelTypeSyncProxyImpl>& sync_proxy_impl) OVERRIDE;
     45 
     46   // Disables syncing for the given type on the sync thread.
     47   virtual void Disconnect(syncer::ModelType type) OVERRIDE;
     48 
     49   virtual scoped_ptr<SyncContextProxy> Clone() const OVERRIDE;
     50 
     51  private:
     52   // A SequencedTaskRunner representing the thread where the SyncContext lives.
     53   scoped_refptr<base::SequencedTaskRunner> sync_task_runner_;
     54 
     55   // The SyncContext this object is wrapping.
     56   base::WeakPtr<SyncContext> sync_context_;
     57 };
     58 
     59 }  // namespace syncer
     60 
     61 #endif  // SYNC_INTERNAL_API_SYNC_CONTEXT_PROXY_IMPL_H_
     62