Version: M52 Canary 52.0.2740.0
OS: Mac 10.11.5

What steps will reproduce the problem?
(1) Establish a 2 way apprtc call https://appr.tc/?vsc=h264 b/w Mac (10.11.5 Macbook Air) and Goobuntu (14.04 LTS) 
(2) Stay in the call for 5 mins or more
(3) Open up chrome://webrtc-internals in another tab to expand the stats graph for send (video) and stats graph for bwevideo
(4) Notice the bitsSentPerSecond and googAvailableSendBandwidth respectively
(Mac is in Google-A n/w and Goobuntu is in a wired n/w)

What is the expected output?
in H.264 apprtc call, you should see the same dip in googAvailableSendBandwidth as bitsSentPerSecond 

What do you see instead?
the dip is not approx in the same range. It varies as seen in the screenshots below

Shot 1:
stats graph for send (video) - https://screenshot.googleplex.com/8MNCPkXghKr.png
stats graph for bwevideo - https://screenshot.googleplex.com/E0UPw7vMEpg.png

Shot 2:
stats graph for send (video) - https://screenshot.googleplex.com/V3sSuiQ1WBS.png
stats graph for bwevideo - https://screenshot.googleplex.com/H9QUOe5J8oy.png

Please use labels and text to provide additional information.
1. With vp8, the googFrameRateSent stayed constant at 30 fps