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

ios/chrome/browser/sync/ios_chrome_sync_client.mm

Index: ios/chrome/browser/sync/ios_chrome_sync_client.mm
diff --git a/ios/chrome/browser/sync/ios_chrome_sync_client.mm b/ios/chrome/browser/sync/ios_chrome_sync_client.mm
index 8d7d4a566576ad89405ed7eabfc4f9b9fea8d4bf..92250fdffc2c57c80135401bbc9da60cbbfa00f5 100644
--- a/ios/chrome/browser/sync/ios_chrome_sync_client.mm
+++ b/ios/chrome/browser/sync/ios_chrome_sync_client.mm
@@ -186,6 +186,10 @@ PrefService* IOSChromeSyncClient::GetPrefService() {
   return browser_state_->GetPrefs();
 }
 
+base::FilePath IOSChromeSyncClient::GetLocalSyncBackendFolder() {
+  return base::FilePath();
+}
+
 bookmarks::BookmarkModel* IOSChromeSyncClient::GetBookmarkModel() {
   DCHECK_CURRENTLY_ON(web::WebThread::UI);
   return ios::BookmarkModelFactory::GetForBrowserState(browser_state_);