Make sync's change processors sequence-affine.

components/sync/driver/generic_change_processor.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 COMPONENTS_SYNC_DRIVER_GENERIC_CHANGE_PROCESSOR_H_
 #define COMPONENTS_SYNC_DRIVER_GENERIC_CHANGE_PROCESSOR_H_
 
 #include <stdint.h>
 
 #include <memory>
 #include <string>
 #include <vector>
 
 #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/model/attachments/attachment_service.h"
 #include "components/sync/model/attachments/attachment_service_proxy.h"
 #include "components/sync/model/attachments/attachment_store.h"
 #include "components/sync/model/change_processor.h"
 #include "components/sync/model/data_type_error_handler.h"
 #include "components/sync/model/sync_change_processor.h"
 #include "components/sync/model/sync_merge_result.h"
 
 namespace syncer {
 
 class SyncClient;
 class SyncData;
 class SyncableService;
 class WriteNode;
 class WriteTransaction;
 
 namespace syncable {
 class Entry;
 }  // namespace syncable
 
 typedef std::vector<SyncData> SyncDataList;
 
 // Datatype agnostic change processor. One instance of GenericChangeProcessor
-// is created for each datatype and lives on the datatype's thread. It then
+// is created for each datatype and lives on the datatype's sequence. It then
 // handles all interaction with the sync api, both translating pushes from the
 // local service into transactions and receiving changes from the sync model,
 // which then get converted into SyncChange's and sent to the local service.
 //
 // As a rule, the GenericChangeProcessor is not thread safe, and should only
-// be used on the same thread in which it was created.
+// be used on the same sequence in which it was created.
 class GenericChangeProcessor : public ChangeProcessor,
                                public SyncChangeProcessor,
-                               public AttachmentService::Delegate,
-                               public base::NonThreadSafe {
+                               public AttachmentService::Delegate {
  public:
   // Create a change processor for |type| and connect it to the syncer.
   // |attachment_store| can be null which means that datatype will not use sync
   // attachments.
   GenericChangeProcessor(
       ModelType type,
       std::unique_ptr<DataTypeErrorHandler> error_handler,
       const base::WeakPtr<SyncableService>& local_service,
       const base::WeakPtr<SyncMergeResult>& merge_result,
       UserShare* user_share,
@@ skipping 78 matching lines @@
 
   // Begin uploading attachments that have not yet been uploaded to the sync
   // server.
   void UploadAllAttachmentsNotOnServer();
 
   // Notify every registered local change observer that |change| is about to be
   // applied to |current_entry|.
   void NotifyLocalChangeObservers(const syncable::Entry* current_entry,
                                   const SyncChange& change);
 
+  base::SequenceChecker sequence_checker_;
+
   const ModelType type_;
 
   // The SyncableService this change processor will forward changes on to.
   const base::WeakPtr<SyncableService> local_service_;
 
   // A SyncMergeResult used to track the changes made during association. The
   // owner will invalidate the weak pointer when association is complete. While
   // the pointer is valid though, we increment it with any changes received
   // via ProcessSyncChanges.
   const base::WeakPtr<SyncMergeResult> merge_result_;
@@ skipping 25 matching lines @@
       attachment_service_weak_ptr_factory_;
   AttachmentServiceProxy attachment_service_proxy_;
   base::WeakPtrFactory<GenericChangeProcessor> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(GenericChangeProcessor);
 };
 
 }  // namespace syncer
 
 #endif  // COMPONENTS_SYNC_DRIVER_GENERIC_CHANGE_PROCESSOR_H_