875862ca86
This change adds code that lets Opus increase the complexity setting at low bitrates (only relevant for mobile where the default complexity is not already maximum). The feature is default off. Also adding a performance test to make sure the complexity adaptation has desired effect. BUG=webrtc:6708 Review-Url: https://codereview.webrtc.org/2503443002 Cr-Commit-Position: refs/heads/master@{#15182}