The timescale_holdoff_ is a counter in the DecisionLogic class. The purpose is to enforce a minimum number of GetAudio calls between (successfull) time-scaling operations (i.e., Accelerate and Pre-emptive Expand operations). With this change, the counter is replaced with a Countdown timer obtained from a TickTimer object. BUG=webrtc:5608 R=tina.legrand@webrtc.org Review URL: https://codereview.webrtc.org/1945863002 . Cr-Commit-Position: refs/heads/master@{#12670}