Remove deprecated CONTENT_SETTINGS_TYPE_METRO_SWITCH_TO_DESKTOP content setting

Remove deprecated CONTENT_SETTINGS_TYPE_METRO_SWITCH_TO_DESKTOP content setting

This content setting was used for a "Don't ask again" button on the Metro mode infobar, but it appears that got removed at the behest of UI review (https://codereview.chromium.org/23591005) a while ago, so we can remove the setting completely.

BUG=512683
Committed: https://crrev.com/58a07059347a10730c3d0e70bbc189c1c21bae49
Cr-Commit-Position: refs/heads/master@{#342572}

[raymes, 2015-08-07 00:57:52]

raymes@chromium.org changed reviewers:
+ bauerb@google.com

[raymes, 2015-08-07 00:57:52]

Thanks for the info Bernhard.

[raymes, 2015-08-07 00:58:07]

The CQ bit was checked by raymes@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-08-07 00:58:33]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1274383002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1274383002/1

[commit-bot: I haz the power, 2015-08-07 01:41:03]

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

[commit-bot: I haz the power, 2015-08-07 01:41:04]

Dry run: Try jobs failed on following builders:
  mac_chromium_rel_ng on tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_rel_...)
  win_chromium_x64_rel_ng on tryserver.chromium.win (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_x64_...)

[Bernhard Bauer, 2015-08-07 07:57:28]

bauerb@chromium.org changed reviewers:
+ bauerb@chromium.org

[Bernhard Bauer, 2015-08-07 07:57:29]

LGTM!

[raymes, 2015-08-10 00:19:32]

The CQ bit was checked by raymes@chromium.org

[commit-bot: I haz the power, 2015-08-10 00:19:43]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1274383002/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1274383002/20001

[commit-bot: I haz the power, 2015-08-10 01:19:39]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-08-10 01:20:13]

Patchset 2 (id:??) landed as
https://crrev.com/58a07059347a10730c3d0e70bbc189c1c21bae49
Cr-Commit-Position: refs/heads/master@{#342572}