Remove an obsolete NULL test for TabContents in NeedsExtensionWebUI.

Remove an obsolete NULL test for TabContents in NeedsExtensionWebUI.

The code that relied on there being a valid TabContents has changed, so we can
now create an ExtensionWebUI for all extension URLs.

BUG=106255
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=171037

[Matt Perry, 2012-12-03 19:21:37]

+avi, FYI

[Avi (use Gerrit), 2012-12-03 19:23:46]

Thank you.

[Evan Stade, 2012-12-03 19:48:10]

lgtm

[commit-bot: I haz the power, 2012-12-03 20:09:18]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/mpcomplete@chromium.org/11348358/1

[commit-bot: I haz the power, 2012-12-04 01:49:32]

Retried try job too often on mac_rel for step(s) browser_tests

[commit-bot: I haz the power, 2012-12-04 01:51:40]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/mpcomplete@chromium.org/11348358/1

[commit-bot: I haz the power, 2012-12-04 05:22:52]

Retried try job too often on mac_rel for step(s) browser_tests

[commit-bot: I haz the power, 2012-12-04 17:47:36]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/mpcomplete@chromium.org/11348358/1

[commit-bot: I haz the power, 2012-12-04 20:26:39]

Change committed as 171037