Count blacklisting as an extension being disabled. Correctly.

Make ExtensionService::IsExtensionEnabled consider prefs blacklist state
when determining if an extension is enabled before it's loaded or the
service is ready.

BUG=376963
R=yoz@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=273021

[Yoyo Zhou, 2014-05-23 20:49:57]

LGTM

[not at google - send to devlin, 2014-05-23 20:51:32]

The CQ bit was checked by kalman@chromium.org

[commit-bot: I haz the power, 2014-05-23 20:53:00]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/kalman@chromium.org/292223003/20001

[not at google - send to devlin, 2014-05-23 21:11:40]

(I got the wrong BUG, updated if you're curious)

[commit-bot: I haz the power, 2014-05-24 00:21:27]

FYI, CQ is re-trying this CL (attempt #1).
Please consider checking whether the failures are real,
and report flakes to chrome-troopers@google.com.
The failing builders are:
  win_chromium_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/win_chromium_rel/buil...)

[commit-bot: I haz the power, 2014-05-24 02:50:05]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-05-24 02:50:06]

Try jobs failed on following builders:
  win_chromium_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/win_chromium_rel/buil...)

[not at google - send to devlin, 2014-05-27 16:39:46]

The CQ bit was checked by kalman@chromium.org

[commit-bot: I haz the power, 2014-05-27 16:40:20]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/kalman@chromium.org/292223003/20001

[commit-bot: I haz the power, 2014-05-27 20:54:37]

Change committed as 273021