
Currently, the looper of the thread the player is created on is used (or the main looper if this thread doesn't have a looper). To allow more control over the threading, this change lets users specificy the looper which must be used to call player methods and which is used for event callbacks. Issue:#4278 ------------- Created by MOE: https://github.com/google/moe MOE_MIGRATED_REVID=201331564