[sync] Clean up path generation for the local sync database.

components/sync/driver/fake_sync_client.h

Index: components/sync/driver/fake_sync_client.h
diff --git a/components/sync/driver/fake_sync_client.h b/components/sync/driver/fake_sync_client.h
index 8a8928d7352778f46503bf788f20556cf8441e17..a5e8b484493203ed8331b1ac14441407e8e234fb 100644
--- a/components/sync/driver/fake_sync_client.h
+++ b/components/sync/driver/fake_sync_client.h
@@ -7,6 +7,7 @@
 
 #include <memory>
 
+#include "base/files/file_path.h"
 #include "base/macros.h"
 #include "components/sync/driver/sync_client.h"
 #include "components/sync_preferences/testing_pref_service_syncable.h"
@@ -26,6 +27,7 @@ class FakeSyncClient : public SyncClient {
 
   SyncService* GetSyncService() override;
   PrefService* GetPrefService() override;
+  base::FilePath GetLocalSyncBackendFolder() override;
   bookmarks::BookmarkModel* GetBookmarkModel() override;
   favicon::FaviconService* GetFaviconService() override;
   history::HistoryService* GetHistoryService() override;