Move l10n_util's GetCanonicalLocal() function into base/i18n module.

Move l10n_util's GetCanonicalLocal() function into base/i18n module.

This removes the base version that takes const char*, and replace it by the one that takes const std::string&. Consolidating this code in one place and having a single function, instead of two with the same name in two different places.

This is a redo of a patch that started in
https://codereview.chromium.org/269943004/

and of another try that was made in
https://codereview.chromium.org/834183005/.

BUG=None
TEST=base_unittests, ui_base_unittests and chrome.
R=sky@chromium.org,thakis@chromium.org

Committed: https://crrev.com/70dff4fc82ac26c9beecc54644ab7ee055596862
Cr-Commit-Position: refs/heads/master@{#311781}

[tfarina, 2015-01-14 13:25:36]

PTAL

[tfarina, 2015-01-15 15:55:06]

Scott, could you please take another look?

I have fixed the chromeos error!

[sky, 2015-01-15 18:35:10]

You need a base owner to review first.

[Nico, 2015-01-15 19:32:10]

the cl description sounds like you're adding another function to base, but
you're only changing the parameter type of an existing function. lgtm (for base
and ui) with reworded cl description

[Nico, 2015-01-15 19:32:26]

On 2015/01/15 19:32:10, Nico wrote:
> the cl description sounds like you're adding another function to base, but
> you're only changing the parameter type of an existing function. lgtm (for
base
> and ui

and chrome

>) with reworded cl description

[tfarina, 2015-01-15 21:26:01]

CL description updated.

[Nico, 2015-01-15 21:28:21]

lgtm

[tfarina, 2015-01-15 23:37:29]

The CQ bit was checked by tfarina@chromium.org

[commit-bot: I haz the power, 2015-01-15 23:39:14]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/846373002/20001

[commit-bot: I haz the power, 2015-01-16 00:37:42]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-01-16 00:38:47]

Patchset 2 (id:??) landed as
https://crrev.com/70dff4fc82ac26c9beecc54644ab7ee055596862
Cr-Commit-Position: refs/heads/master@{#311781}