Adding @IntDef checking for Video Quality and Video State values.

Admittedly this isn't going to cause a build breakage for anyone misusing
the values, but it should help make issues more aware at code authoring
time.

See http://goo.gl/zaH4RE for more information.

Change-Id: I3f20dc4bff364dec290d4b647e31f8032d4a13ec