Refactor to reduce main loop complexity. Bug: angleproject:7299 Change-Id: I157e84b7a6718d59eecb00471d4ec7ae5b3317cf Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3831885 Commit-Queue: Roman Lavrov <romanl@google.com> Reviewed-by: Amirali Abdolrashidi <abdolrashidi@google.com>