sync: move SharedChangeProcessor to components/

chrome/browser/sync/glue/shared_change_processor.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_SHARED_CHANGE_PROCESSOR_H_
-#define CHROME_BROWSER_SYNC_GLUE_SHARED_CHANGE_PROCESSOR_H_
-
-#include "base/location.h"
-#include "base/memory/ref_counted.h"
-#include "base/memory/weak_ptr.h"
-#include "base/message_loop/message_loop_proxy.h"
-#include "base/synchronization/lock.h"
-#include "components/sync_driver/data_type_error_handler.h"
-#include "sync/api/sync_change_processor.h"
-#include "sync/api/sync_data.h"
-#include "sync/api/sync_error.h"
-#include "sync/api/sync_error_factory.h"
-#include "sync/api/sync_merge_result.h"
-#include "sync/internal_api/public/engine/model_safe_worker.h"
-
-class ProfileSyncService;
-
-namespace syncer {
-class SyncableService;
-struct UserShare;
-}  // namespace syncer
-
-namespace browser_sync {
-
-class ChangeProcessor;
-class GenericChangeProcessor;
-class GenericChangeProcessorFactory;
-class DataTypeErrorHandler;
-class SyncApiComponentFactory;
-
-// A ref-counted wrapper around a GenericChangeProcessor for use with datatypes
-// that don't live on the UI thread.
-//
-// We need to make it refcounted as the ownership transfer from the
-// DataTypeController is dependent on threading, and hence racy. The
-// SharedChangeProcessor should be created on the UI thread, but should only be
-// connected and used on the same thread as the datatype it interacts with.
-//
-// The only thread-safe method is Disconnect, which will disconnect from the
-// generic change processor, letting us shut down the syncer/datatype without
-// waiting for non-UI threads.
-//
-// Note: since we control the work being done while holding the lock, we ensure
-// no I/O or other intensive work is done while blocking the UI thread (all
-// the work is in-memory sync interactions).
-//
-// We use virtual methods so that we can use mock's in testing.
-class SharedChangeProcessor
-    : public base::RefCountedThreadSafe<SharedChangeProcessor> {
- public:
-  // Create an uninitialized SharedChangeProcessor.
-  SharedChangeProcessor();
-
-  // Connect to the Syncer and prepare to handle changes for |type|. Will
-  // create and store a new GenericChangeProcessor and return a weak pointer to
-  // the syncer::SyncableService associated with |type|.
-  // Note: If this SharedChangeProcessor has been disconnected, or the
-  // syncer::SyncableService was not alive, will return a null weak pointer.
-  virtual base::WeakPtr<syncer::SyncableService> Connect(
-      browser_sync::SyncApiComponentFactory* sync_factory,
-      GenericChangeProcessorFactory* processor_factory,
-      syncer::UserShare* user_share,
-      DataTypeErrorHandler* error_handler,
-      syncer::ModelType type,
-    const base::WeakPtr<syncer::SyncMergeResult>& merge_result);
-
-  // Disconnects from the generic change processor. May be called from any
-  // thread. After this, all attempts to interact with the change processor by
-  // |local_service_| are dropped and return errors. The syncer will be safe to
-  // shut down from the point of view of this datatype.
-  // Note: Once disconnected, you cannot reconnect without creating a new
-  // SharedChangeProcessor.
-  // Returns: true if we were previously succesfully connected, false if we were
-  // already disconnected.
-  virtual bool Disconnect();
-
-  // GenericChangeProcessor stubs (with disconnect support).
-  // Should only be called on the same thread the datatype resides.
-  virtual int GetSyncCount();
-  virtual syncer::SyncError ProcessSyncChanges(
-      const tracked_objects::Location& from_here,
-      const syncer::SyncChangeList& change_list);
-  virtual syncer::SyncDataList GetAllSyncData(syncer::ModelType type) const;
-  virtual syncer::SyncError GetAllSyncDataReturnError(
-      syncer::ModelType type,
-      syncer::SyncDataList* data) const;
-  virtual syncer::SyncError UpdateDataTypeContext(
-      syncer::ModelType type,
-      syncer::SyncChangeProcessor::ContextRefreshStatus refresh_status,
-      const std::string& context);
-  virtual bool SyncModelHasUserCreatedNodes(bool* has_nodes);
-  virtual bool CryptoReadyIfNecessary();
-
-  // If a datatype context associated with the current type exists, fills
-  // |context| and returns true. Otheriwse, if there has not been a context
-  // set, returns false.
-  virtual bool GetDataTypeContext(std::string* context) const;
-
-  virtual syncer::SyncError CreateAndUploadError(
-      const tracked_objects::Location& location,
-      const std::string& message);
-
-  ChangeProcessor* generic_change_processor();
-
- protected:
-  friend class base::RefCountedThreadSafe<SharedChangeProcessor>;
-  virtual ~SharedChangeProcessor();
-
- private:
-  // Monitor lock for this object. All methods that interact with the change
-  // processor must aquire this lock and check whether we're disconnected or
-  // not. Once disconnected, all attempted changes to or loads from the change
-  // processor return errors. This enables us to shut down the syncer without
-  // having to wait for possibly non-UI thread datatypes to complete work.
-  mutable base::Lock monitor_lock_;
-  bool disconnected_;
-
-  // The sync datatype we were last connected to.
-  syncer::ModelType type_;
-
-  // The frontend / UI MessageLoop this object is constructed on. May also be
-  // destructed and/or disconnected on this loop, see ~SharedChangeProcessor.
-  const scoped_refptr<const base::MessageLoopProxy> frontend_loop_;
-
-  // The loop that all methods except the constructor, destructor, and
-  // Disconnect() should be called on.  Set in Connect().
-  scoped_refptr<base::MessageLoopProxy> backend_loop_;
-
-  // Used only on |backend_loop_|.
-  GenericChangeProcessor* generic_change_processor_;
-
-  DataTypeErrorHandler* error_handler_;
-
-  DISALLOW_COPY_AND_ASSIGN(SharedChangeProcessor);
-};
-
-}  // namespace browser_sync
-
-#endif  // CHROME_BROWSER_SYNC_GLUE_SHARED_CHANGE_PROCESSOR_H_