[Sync] Migrate bridge implementations to change list based MergeSyncData

components/sync/user_events/user_event_sync_bridge.h

 // Copyright 2017 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_USER_EVENTS_USER_EVENT_SYNC_BRIDGE_H_
 #define COMPONENTS_SYNC_USER_EVENTS_USER_EVENT_SYNC_BRIDGE_H_
 
 #include <memory>
 #include <string>
 
 #include "base/macros.h"
 #include "components/sync/model/model_type_store.h"
 #include "components/sync/model/model_type_sync_bridge.h"
 
 namespace syncer {
 
 class UserEventSyncBridge : public ModelTypeSyncBridge {
  public:
   UserEventSyncBridge(const ModelTypeStoreFactory& store_factory,
                       const ChangeProcessorFactory& change_processor_factory);
   ~UserEventSyncBridge() override;
 
   // ModelTypeSyncBridge implementation.
   std::unique_ptr<MetadataChangeList> CreateMetadataChangeList() override;
   base::Optional<ModelError> MergeSyncData(
       std::unique_ptr<MetadataChangeList> metadata_change_list,
-      EntityDataMap entity_data_map) override;
+      EntityChangeList entity_data) override;
   base::Optional<ModelError> ApplySyncChanges(
       std::unique_ptr<MetadataChangeList> metadata_change_list,
       EntityChangeList entity_changes) override;
   void GetData(StorageKeyList storage_keys, DataCallback callback) override;
   void GetAllData(DataCallback callback) override;
   std::string GetClientTag(const EntityData& entity_data) override;
   std::string GetStorageKey(const EntityData& entity_data) override;
   void DisableSync() override;
 
   void RecordUserEvent(std::unique_ptr<sync_pb::UserEventSpecifics> specifics);
@@ skipping 18 matching lines @@
   // Persistent storage for in flight events. Should remain quite small, as we
   // delete upon commit confirmation.
   std::unique_ptr<ModelTypeStore> store_;
 
   DISALLOW_COPY_AND_ASSIGN(UserEventSyncBridge);
 };
 
 }  // namespace syncer
 
 #endif  // COMPONENTS_SYNC_USER_EVENTS_USER_EVENT_SYNC_BRIDGE_H_