Simplify test locales in ui_unittests Framework

Simplify test locales in Mac's ui_unittests Framework

Mac creates a mini-framework in `ui_unittests Framework` so that ui
tests can get a resource bundle without depending on the Chrome
framework. 

The way it generated locale information was causing build flakes since
two instances of repack_locales.py could be writing to
out/../gen/repack. Tests always use en-US, so instead just do what iOS
does and copy ui_test.pak to en.lproj/locale.pak and roll it into the
mini-framework bundle.

BUG=410468
Committed: https://crrev.com/bac8fafd3d056f1277c2fdf44d2a66ca19252e54
Cr-Commit-Position: refs/heads/master@{#294052}

[tapted, 2014-09-09 08:24:33]

tapted@chromium.org changed reviewers:
+ thakis@chromium.org

[tapted, 2014-09-09 08:36:58]

tapted@chromium.org changed reviewers:
+ avi@chromium.org
- thakis@chromium.org

[tapted, 2014-09-09 08:55:32]

Hi Avi, please take a look. I've tested this in a clobber build; just building
and running ui_unittests still seems happy, with just the single locale and no
dependency issues. Thanks!

[Avi (use Gerrit), 2014-09-09 14:11:27]

lgtm

That's fine.

[tapted, 2014-09-09 23:19:16]

The CQ bit was checked by tapted@chromium.org

[commit-bot: I haz the power, 2014-09-09 23:25:19]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/tapted@chromium.org/552963002/1

[commit-bot: I haz the power, 2014-09-10 00:36:23]

Committed patchset #1 (id:1) as 5b46b6a3166fdccbde174e84c2f3f363ea1d08e4

[commit-bot: I haz the power, 2014-09-10 03:57:00]

Patchset 1 (id:??) landed as
https://crrev.com/bac8fafd3d056f1277c2fdf44d2a66ca19252e54
Cr-Commit-Position: refs/heads/master@{#294052}

[tapted, 2014-09-11 05:18:58]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/560993004/ by tapted@chromium.org.

The reason for reverting is: Bizarrely, this is causing valgrind on Snow Leopard
to pick up a
bunch of leaks from allocations within system libraries.
Reverting while I figure out how best to fix that.

BUG=413034.