Reason for revert:
Tasn test failure.
Original issue's description:
> Add first part of the network_tester functionality.
>
> BUG=webrtc:7426
>
> Review-Url: https://codereview.webrtc.org/2779233002
> Cr-Commit-Position: refs/heads/master@{#17635}
> Committed: 333d0ff631TBR=stefan@webrtc.org,minyue@webrtc.org,nisse@webrtc.org,terelius@webrtc.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=webrtc:7426
Review-Url: https://codereview.webrtc.org/2800403003
Cr-Commit-Position: refs/heads/master@{#17636}
7fb7bbd179