Revert 230925 "Speculatively disabling ExtensionServiceTest.SetU..."
The bot continued to fail after disabling the test.
> Speculatively disabling ExtensionServiceTest.SetUnsetBlacklistInPrefs
>
> chromium.webkit Vista Tests keeps failing on it:
> http://build.chromium.org/p/chromium.webkit/builders/Vista%20Tests/builds/34132/
>
> This bot has had issues for the past two weeks. It may be a deeper problem.
>
> BUG=310941
> TBR=jsbell
>
> Review URL: https://codereview.chromium.org/
43053002
TBR=falken@chromium.org
Review URL: https://codereview.chromium.org/
43303002
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@230966 0039d316-1c4b-4281-b951-d872f2087c98