[Sync] Introduce ModelError for USS error handling.

components/sync/device_info/device_info_sync_bridge.h

Index: components/sync/device_info/device_info_sync_bridge.h
diff --git a/components/sync/device_info/device_info_sync_bridge.h b/components/sync/device_info/device_info_sync_bridge.h
index 5af1995f7860bfed7216b82880b19f28ea3d9b2d..9aeabe87b4e7f61516682bdfa9d437d881bd254a 100644
--- a/components/sync/device_info/device_info_sync_bridge.h
+++ b/components/sync/device_info/device_info_sync_bridge.h
@@ -26,8 +26,6 @@ class DeviceInfoSpecifics;
 
 namespace syncer {
 
-class SyncError;
-
 // Sync bridge implementation for DEVICE_INFO model type. Handles storage of
 // device info and associated sync metadata, applying/merging foreign changes,
 // and allows public read access.
@@ -44,10 +42,10 @@ class DeviceInfoSyncBridge : public ModelTypeSyncBridge,
 
   // ModelTypeSyncBridge implementation.
   std::unique_ptr<MetadataChangeList> CreateMetadataChangeList() override;
-  SyncError MergeSyncData(
+  ModelError MergeSyncData(
       std::unique_ptr<MetadataChangeList> metadata_change_list,
       EntityDataMap entity_data_map) override;
-  SyncError ApplySyncChanges(
+  ModelError ApplySyncChanges(
       std::unique_ptr<MetadataChangeList> metadata_change_list,
       EntityChangeList entity_changes) override;
   void GetData(StorageKeyList storage_keys, DataCallback callback) override;
@@ -91,7 +89,7 @@ class DeviceInfoSyncBridge : public ModelTypeSyncBridge,
                       std::unique_ptr<ModelTypeStore> store);
   void OnReadAllData(ModelTypeStore::Result result,
                      std::unique_ptr<ModelTypeStore::RecordList> record_list);
-  void OnReadAllMetadata(SyncError error,
+  void OnReadAllMetadata(ModelError error,
                          std::unique_ptr<MetadataBatch> metadata_batch);
   void OnCommit(ModelTypeStore::Result result);
 
@@ -119,10 +117,6 @@ class DeviceInfoSyncBridge : public ModelTypeSyncBridge,
   // allow unit tests to control expected results.
   int CountActiveDevices(const base::Time now) const;
 
-  // Report an error starting up to sync if it tries to connect to this
-  // datatype, since these errors prevent us from knowing if sync is enabled.
-  void ReportStartupErrorToSync(const std::string& msg);
-
   // |local_device_info_provider_| isn't owned.
   const LocalDeviceInfoProvider* const local_device_info_provider_;