Fix SDK forward declarations after CL 530193004

The APIs that need forward declarations were actually introduced in
OS X 10.7 SDK instead of 10.9 SDK, forward declare them in the wrong
place will cause build issue when using older SDKs like 10.7 or 10.8.


Review URL:

Cr-Commit-Position: refs/heads/master@{#294013}
1 file changed