Fix bug which causes the PlayerActivity to finish whenever the
android.permission.READ_EXTERNAL_STORAGE permission is requested.
A better solution would involve not requesting permissions if a
previous request is still pending. This would involve keeping
extra state in the activity, so this solution is used to keep
the demo app's complexity at a minimum.
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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=192588821
