The intended behavior of the pacer is that it should send audio (i.e high priority) packets immediatelly even if the pacer is paused and even if the available media budget has been used. The existing code will not send audio if the pacing budget has been used. It will normally send audio when the pacer is paused, but if the media budget was already used up when the pacer was paused, it would neither send audio nor update the budget.
Updated the implementatation and the unit test. Added logging for when the pacer is paused, and when it receives a zero bitrate estimate.
BUG=webrtc:6155
Review-Url: https://codereview.webrtc.org/2193183003
Cr-Commit-Position: refs/heads/master@{#13592}
8b70faf262