receive a signal level to use initially, instead of the default initial signal level. BUG= Review-Url: https://codereview.webrtc.org/2254973003 Cr-Commit-Position: refs/heads/master@{#13931}
NOTRY=true TBR=aluebs@webrtc.org BUG=webrtc:5920 Review-Url: https://codereview.webrtc.org/2090583002 Cr-Commit-Position: refs/heads/master@{#13333}