Added 250p scale factor.

Recent update to Windows 8.1 added new default High DPI mode - 250% for qHD displays.
This is initial work package to reflect this change, making it possible to add hi-resolution resources in the future (if needed).

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=276551

[cpu_(ooo_6.6-7.5), 2014-06-10 01:28:29]

lgtm

please flesh out the CL description. Like why do this, what is the motivation
and what should we expect, if there is a bug number add it too.

[Mateusz Szymański, 2014-06-10 08:14:24]

The CQ bit was checked by mateuszs@opera.com

[commit-bot: I haz the power, 2014-06-10 08:17:01]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/mateuszs@opera.com/327503003/1

[commit-bot: I haz the power, 2014-06-10 19:35:25]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  chromium_presubmit on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/chromium_presubmit/bu...)
  win_chromium_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/win_chromium_rel/buil...)

[commit-bot: I haz the power, 2014-06-10 19:38:44]

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

[commit-bot: I haz the power, 2014-06-10 19:38:45]

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

[Mateusz Szymański, 2014-06-11 07:34:01]

Can I have LGTM once more please?

[sky, 2014-06-11 16:07:44]

LGTM

[Mateusz Szymański, 2014-06-12 06:28:59]

The CQ bit was checked by mateuszs@opera.com

[commit-bot: I haz the power, 2014-06-12 06:33:34]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/mateuszs@opera.com/327503003/1

[commit-bot: I haz the power, 2014-06-12 06:42:30]

Change committed as 276551