Reason for revert:
Fixed
Original issue's description:
> Revert of Trace the stats report as JSON instead of each stat separately. (patchset #3 id:100001 of https://codereview.webrtc.org/2986453002/ )
>
> Reason for revert:
> It breaks a downstream project.
>
> Original issue's description:
> > Trace the stats report as JSON instead of each stat separately.
> >
> > Trace the whole report as a string instead of each field on it's own. And test that the traces collected are valid.
> >
> > R=tommi@webrtc.org, hbos@webrtc.org
> > BUG=chromium:653087
> >
> > Review-Url: https://codereview.webrtc.org/2986453002
> > Cr-Commit-Position: refs/heads/master@{#19341}
> > Committed: 80c65780e6
>
> TBR=hbos@webrtc.org,tommi@webrtc.org,ehmaldonado@webrtc.org
> # Skipping CQ checks because original CL landed less than 1 days ago.
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
> BUG=chromium:653087
>
> Review-Url: https://codereview.webrtc.org/3001683002
> Cr-Commit-Position: refs/heads/master@{#19344}
> Committed: 3439c89358
BUG=chromium:653087
Review-Url: https://codereview.webrtc.org/3000943002
Cr-Commit-Position: refs/heads/master@{#19673}
8ab0fd80ad