[Sync] Migrate bridge implementations to change list based MergeSyncData

components/sync/model/entity_data.h

 // Copyright 2015 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_MODEL_ENTITY_DATA_H_
 #define COMPONENTS_SYNC_MODEL_ENTITY_DATA_H_
 
 #include <map>
 #include <memory>
 #include <string>
@@ skipping 10 matching lines @@
 struct EntityData;
 
 struct EntityDataTraits {
   static void SwapValue(EntityData* dest, EntityData* src);
   static bool HasValue(const EntityData& value);
   static const EntityData& DefaultValue();
 };
 
 using EntityDataPtr = ProtoValuePtr<EntityData, EntityDataTraits>;
 using EntityDataList = std::vector<EntityDataPtr>;
-using EntityDataMap = std::map<std::string, EntityDataPtr>;
 
 // A light-weight container for sync entity data which represents either
 // local data created on the ModelTypeSyncBridge side or remote data created
 // on ModelTypeWorker.
 // EntityData is supposed to be wrapped and passed by reference.
 struct EntityData {
  public:
   EntityData();
   ~EntityData();
 
@@ skipping 44 matching lines @@
   friend struct EntityDataTraits;
   // Used to transfer the data without copying.
   void Swap(EntityData* other);
 
   DISALLOW_COPY_AND_ASSIGN(EntityData);
 };
 
 }  // namespace syncer
 
 #endif  // COMPONENTS_SYNC_MODEL_ENTITY_DATA_H_