Fix render after backgrounding crash
Fix render after backgrounding crash

Summary: There is a little time after background when we still have cpu time, enough to call some gl functions, which crash. It's apparently not kosher to render after backgrounding.

Test Plan: run app on iphone, background app and un-background it a few times. Confirm no crash.

Reviewers: mike.naquin

Reviewed By: mike.naquin

Subscribers: cbrown

Differential Revision: https://phabricator.watchonair.tv/D902

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