The media related stats wasn't working for unsignaled stream because there
is no mapping between the receiver_info and unsignaled tracks.
This CL fixes the issue by adding some special logic to the TrackMediaInfoMap
which would create the mapping.
BUG=b/37836881
BUG=webrtc:7685
TBR=deadbeef@webrtc.org
Review-Url: https://codereview.webrtc.org/2883943003
Cr-Commit-Position: refs/heads/master@{#18217}
Running video loopback on https://appr.tc/ revealed that it is possible
to use the same SSRC for a local and remote audio or video track. This
caused a DCHECK crash. The constructor of TrackMediaInfoMap is updated
to support this mapping and the unittest is updated (moved and modified
a test from being a death test to being a non-death test).
I've verified that this fixes the bug.
BUG=chromium:693087
Review-Url: https://codereview.webrtc.org/2703783002
Cr-Commit-Position: refs/heads/master@{#16713}