Add missing DETECT_IMPORTANT_CONTENT value to ContentSetting enum in UMA histograms.

Add missing DETECT_IMPORTANT_CONTENT value to ContentSetting enum in UMA histograms.

This was accidentally missed in https://chromium.googlesource.com/chromium/src/+/a23713b67ee741e5bb026d99e86b8c97cc9ab84d

BUG=

Committed: https://crrev.com/31f774df0083901a2023ffb69894eeef3add6f69
Cr-Commit-Position: refs/heads/master@{#339741}

[lgarron, 2015-07-14 21:07:43]

lgarron@chromium.org changed reviewers:
+ isherman@chromium.org

[lgarron, 2015-07-14 21:13:45]

On 2015/07/14 at 21:07:44, lgarron wrote:
> 

https://goto.google.com/uma-histograms?histograms=ContentSettings.DefaultPlug...
also shows some edge cases where people send the `DEFAULT` value [1]. I don't
know if it's worth adding that.



[1]
https://code.google.com/p/chromium/codesearch#chromium/src/components/content...

[Ilya Sherman, 2015-07-16 01:53:11]

LGTM.  No reason that I can think of not to add an entry for DEFAULT as well.

[lgarron, 2015-07-21 19:10:05]

Cool, I've added DEFAULT.

[lgarron, 2015-07-21 19:10:06]

The CQ bit was checked by lgarron@chromium.org

[lgarron, 2015-07-21 19:10:06]

The patchset sent to the CQ was uploaded after l-g-t-m from
isherman@chromium.org
Link to the patchset: https://codereview.chromium.org/1238623003/#ps20001
(title: "Add DEFAULT, too.")

[commit-bot: I haz the power, 2015-07-21 19:11:28]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1238623003/20001

[commit-bot: I haz the power, 2015-07-21 20:38:58]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-07-21 20:39:51]

Patchset 2 (id:??) landed as
https://crrev.com/31f774df0083901a2023ffb69894eeef3add6f69
Cr-Commit-Position: refs/heads/master@{#339741}