Fix up extension sandbox tests.
Fix up extension sandbox tests.

This fixes up some naming and use of deprecated methods in the sandbox unit
tests.

Testing done:
Ran unit tests.

Reviewed at https://reviews.reviewboard.org/r/8077/

sgallagher/reviewboard,chipx86/reviewboard,chipx86/reviewboard,reviewboard/reviewboard,reviewboard/reviewboard,reviewboard/reviewboard,davidt/reviewboard,chipx86/reviewboard,brennie/reviewboard,davidt/reviewboard,davidt/reviewboard,reviewboard/reviewboard,sgallagher/reviewboard,brennie/reviewboard,sgallagher/reviewboard,chipx86/reviewboard,davidt/reviewboard,brennie/reviewboard,sgallagher/reviewboard,brennie/reviewboard