Revert of Disabling failing tests in WebRtcApprtcBrowserTest (patchset #2 id:20001...

Revert of Disabling failing tests in WebRtcApprtcBrowserTest (patchset #2 id:20001 of https://codereview.chromium.org/1016693002/)

Reason for revert:
We have landed an update to the AppRTC app in https://codereview.chromium.org/1023683002/ now, so these tests should now work.

Original issue's description:
> Disabling failing tests in WebRtcApprtcBrowserTest.
>
> These tests will be enabled again once the AppRTC app is working again which we expect will happen rather soon.
>
> TBR=phoglund
> BUG=467471
>
> Committed: https://crrev.com/15103a5ff0f262c85309d4b6af957d7c089aab3d
> Cr-Commit-Position: refs/heads/master@{#320883}

TBR=phoglund@chromium.org,henrika@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=467471

Review URL: https://codereview.chromium.org/1027673002

Cr-Commit-Position: refs/heads/master@{#321527}