[Sync] Migrate bridge implementations to change list based MergeSyncData

components/sync/device_info/device_info_sync_bridge.cc

 // 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.
 
 #include "components/sync/device_info/device_info_sync_bridge.h"
 
 #include <stdint.h>
 
 #include <algorithm>
 #include <set>
@@ skipping 96 matching lines @@
 
 DeviceInfoSyncBridge::~DeviceInfoSyncBridge() {}
 
 std::unique_ptr<MetadataChangeList>
 DeviceInfoSyncBridge::CreateMetadataChangeList() {
   return WriteBatch::CreateMetadataChangeList();
 }
 
 base::Optional<ModelError> DeviceInfoSyncBridge::MergeSyncData(
     std::unique_ptr<MetadataChangeList> metadata_change_list,
-    EntityDataMap entity_data_map) {
+    EntityChangeList entity_data) {
   DCHECK(has_provider_initialized_);
   DCHECK(change_processor()->IsTrackingMetadata());
   const DeviceInfo* local_info =
       local_device_info_provider_->GetLocalDeviceInfo();
   // If our dependency was yanked out from beneath us, we cannot correctly
   // handle this request, and all our data will be deleted soon.
   if (local_info == nullptr) {
     return {};
   }
 
   // Local data should typically be near empty, with the only possible value
   // corresponding to this device. This is because on signout all device info
   // data is blown away. However, this simplification is being ignored here and
   // a full difference is going to be calculated to explore what other bridge
   // implementations may look like.
   std::set<std::string> local_guids_to_put;
   for (const auto& kv : all_data_) {
     local_guids_to_put.insert(kv.first);
   }
 
   bool has_changes = false;
   std::string local_guid = local_info->guid();
   std::unique_ptr<WriteBatch> batch = store_->CreateWriteBatch();
-  for (const auto& kv : entity_data_map) {
+  for (const auto& change : entity_data) {
     const DeviceInfoSpecifics& specifics =
-        kv.second.value().specifics.device_info();
-    DCHECK_EQ(kv.first, specifics.cache_guid());
+        change.data().specifics.device_info();
+    DCHECK_EQ(change.storage_key(), specifics.cache_guid());
     if (specifics.cache_guid() == local_guid) {
       // Don't Put local data if it's the same as the remote copy.
       if (local_info->Equals(*SpecificsToModel(specifics))) {
         local_guids_to_put.erase(local_guid);
       }
     } else {
       // Remote data wins conflicts.
       local_guids_to_put.erase(specifics.cache_guid());
       has_changes = true;
       StoreSpecifics(base::MakeUnique<DeviceInfoSpecifics>(specifics),
@@ skipping 317 matching lines @@
 
 int DeviceInfoSyncBridge::CountActiveDevices(const Time now) const {
   return std::count_if(all_data_.begin(), all_data_.end(),
                        [now](ClientIdToSpecifics::const_reference pair) {
                          return DeviceInfoUtil::IsActive(
                              GetLastUpdateTime(*pair.second), now);
                        });
 }
 
 }  // namespace syncer