Revert of Revert of Flip extension background page throttling on by default (patchset...

Revert of Revert of Flip extension background page throttling on by default (patchset #1 id:1 of https://codereview.chromium.org/1106953002/)

Reason for revert:
Re-landing, tests fixed in https://codereview.chromium.org/1108133002/

Original issue's description:
> Revert of Flip extension background page throttling on by default (patchset #2 id:20001 of https://codereview.chromium.org/1106653002/)
>
> Reason for revert:
> Speculative revert - multiple browser_tests fail on Mac10.9 Tests (dbg)
> http://goo.gl/4AqhVG
>
> Original issue's description:
> > Flip extension background page throttling on by default
> >
> > R=kalman
> > BUG=424661
> >
> > Committed: https://crrev.com/34ea66b8ac1d56dadd670a9f5f8431063857ffdd
> > Cr-Commit-Position: refs/heads/master@{#326953}
>
> TBR=kalman@chromium.org,oysteine@chromium.org
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
> BUG=424661
>
> Committed: https://crrev.com/76a7e3446188256ca240dc31cd5287ef78de2951
> Cr-Commit-Position: refs/heads/master@{#327021}

TBR=kalman@chromium.org,nkostylev@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=424661

Review URL: https://codereview.chromium.org/1161773008

Cr-Commit-Position: refs/heads/master@{#332062}