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

components/sync/driver/fake_sync_client.cc

Index: components/sync/driver/fake_sync_client.cc
diff --git a/components/sync/driver/fake_sync_client.cc b/components/sync/driver/fake_sync_client.cc
index 16a46df47231558448fd378ac938169b89a36e4b..698c01f65ad81a94b940153715aa64a80ad1fa70 100644
--- a/components/sync/driver/fake_sync_client.cc
+++ b/components/sync/driver/fake_sync_client.cc
@@ -48,6 +48,10 @@ PrefService* FakeSyncClient::GetPrefService() {
   return &pref_service_;
 }
 
+base::FilePath FakeSyncClient::GetLocalSyncBackendFolder() {
+  return base::FilePath();
+}
+
 bookmarks::BookmarkModel* FakeSyncClient::GetBookmarkModel() {
   return nullptr;
 }