Revert of Disable RunsAudioVideoWebRTCCallInTwoTabs so blink can roll (patchset #1 id:1 of https://codereview.chromium.org/1148873003/)
Revert of Disable RunsAudioVideoWebRTCCallInTwoTabs so blink can roll (patchset #1 id:1 of https://codereview.chromium.org/1148873003/)

Reason for revert:
Re-enabling after reverting breaking change.

BUG=490368

Original issue's description:
> Disable RunsAudioVideoWebRTCCallInTwoTabs so blink can roll
>
> This failure has been preventing blink from rolling for >12 hours.
> Sample failure:
>
> http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_rel_ng/builds/66651
>
> TBR=cevans@chromium.org,haraken@chromium.org
> NOTRY=true
> BUG=
>
> Committed: https://crrev.com/44cafa04c9c11b4ac32c99d39177be62b0a7acd3
> Cr-Commit-Position: refs/heads/master@{#330763}

TBR=cevans@chromium.org,haraken@chromium.org,szager@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=

Review URL: https://codereview.chromium.org/1152333004

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#331270}

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