Make getTransactionKey() protected

Test Plan: Search for `getTransactionKey`.

Reviewers: epriestley

Reviewed By: epriestley

CC: aran

Differential Revision: https://secure.phabricator.com/D2115

src/storage/connection/isolated/AphrontIsolatedDatabaseConnection.php

@@ -70,7 +70,7 @@ final class AphrontIsolatedDatabaseConnection
     return $this->affectedRows;
   }
 
-  public function getTransactionKey() {
+  protected function getTransactionKey() {
     return $this->transactionKey;
   }
 

src/storage/connection/mysql/AphrontMySQLDatabaseConnection.php

@@ -192,7 +192,7 @@ final class AphrontMySQLDatabaseConnection extends AphrontDatabaseConnection {
     return mysql_affected_rows($this->requireConnection());
   }
 
-  public function getTransactionKey() {
+  protected function getTransactionKey() {
     return (int)$this->requireConnection();
   }