Expose local sync mode status in the chrome://sync-internals page.

components/sync/engine/sync_status.h

Index: components/sync/engine/sync_status.h
diff --git a/components/sync/engine/sync_status.h b/components/sync/engine/sync_status.h
index 4fa6de31fd7d21985206b8d69680f7a44423e27f..5e38cb0fffa2315df212cfa94956f13fd4228c53 100644
--- a/components/sync/engine/sync_status.h
+++ b/components/sync/engine/sync_status.h
@@ -96,6 +96,9 @@ struct SyncStatus {
 
   // Time of next retry if sync scheduler is throttled or in backoff.
   base::Time retry_time;
+
+  // The location of the local sync backend db file if local sync is enabled.
+  std::string local_sync_folder;
 };
 
 }  // namespace syncer