[Offline Pages] Updated clearing logic in storage manager.

components/offline_pages/archive_manager.cc

Index: components/offline_pages/archive_manager.cc
diff --git a/components/offline_pages/archive_manager.cc b/components/offline_pages/archive_manager.cc
index 9dfeabbe0b0c82460a888db52c37535e5edea693..8df6b541e346fc0d63b8f7a9f63cd11edeee99cf 100644
--- a/components/offline_pages/archive_manager.cc
+++ b/components/offline_pages/archive_manager.cc
@@ -69,6 +69,9 @@ void GetStorageStatsImpl(const base::FilePath& archive_dir,
 
 }  // namespace
 
+// protected and used for testing.
+ArchiveManager::ArchiveManager() {}
+
 ArchiveManager::ArchiveManager(
     const base::FilePath& archives_dir,
     const scoped_refptr<base::SequencedTaskRunner>& task_runner)