[Sync] Refactor sync datatype error handling.

chrome/browser/sync/api/syncable_service_mock.h

 // Copyright (c) 2011 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_API_SYNCABLE_SERVICE_MOCK_H_
 #define CHROME_BROWSER_SYNC_API_SYNCABLE_SERVICE_MOCK_H_
 #pragma once
 
 #include "base/tracked.h"
 #include "chrome/browser/sync/api/syncable_service.h"
 #include "chrome/browser/sync/api/sync_change.h"
 #include "testing/gmock/include/gmock/gmock.h"
 
 class SyncableServiceMock : public SyncableService {
  public:
   SyncableServiceMock();
   virtual ~SyncableServiceMock();
 
-  MOCK_METHOD3(MergeDataAndStartSyncing, bool(
-      syncable::ModelType, const SyncDataList&,
-      SyncChangeProcessor* sync_processor));
+  MOCK_METHOD3(MergeDataAndStartSyncing,
+               SyncError(syncable::ModelType,
+                         const SyncDataList&,
+                         SyncChangeProcessor* sync_processor));
   MOCK_METHOD1(StopSyncing, void(syncable::ModelType));
-  MOCK_CONST_METHOD1(GetAllSyncData, SyncDataList(syncable::ModelType));
+  MOCK_CONST_METHOD1(GetAllSyncData, SyncDataList(syncable::ModelType type));
   MOCK_METHOD2(ProcessSyncChanges,
-               void(const tracked_objects::Location&, const SyncChangeList&));
+               SyncError(const tracked_objects::Location&,
+                         const SyncChangeList&));
 };
 
 #endif  // CHROME_BROWSER_SYNC_API_SYNCABLE_SERVICE_MOCK_H_