Change ExecuteJavaScript* helper functions in browser_test_utils.{h,cc}

Change ExecuteJavaScript* helper functions in browser_test_utils.{h,cc}
to take std::string (UTF-8) instead of std::wstring.  This seems to help
simplify callsites considerably.

TBR=jam@chromium.org
BUG=none


Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=174880

[jam, 2013-01-02 16:04:16]

lgtm

[commit-bot: I haz the power, 2013-01-02 20:46:53]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/darin@chromium.org/11728003/4074

[commit-bot: I haz the power, 2013-01-02 22:44:16]

Change committed as 174880

[gavinp, 2013-01-03 16:33:12]

On 2013/01/02 22:44:16, I haz the power (commit-bot) wrote:
> Change committed as 174880

Note this was reverted in https://codereview.chromium.org/11734018/

[jam, 2013-01-03 16:46:35]

On Thu, Jan 3, 2013 at 8:33 AM, <gavinp@chromium.org> wrote:

> On 2013/01/02 22:44:16, I haz the power (commit-bot) wrote:
>
>> Change committed as 174880
>>
>
> Note this was reverted in
https://codereview.chromium.**org/11734018/<https://codereview.chromium.org/1...


just on a branch...

>
>
>
https://chromiumcodereview.**appspot.com/11728003/<https://chromiumcodereview...
>

[gavinp, 2013-01-03 16:51:29]

On 2013/01/03 16:46:35, John Abd-El-Malek wrote:
> On Thu, Jan 3, 2013 at 8:33 AM, <mailto:gavinp@chromium.org> wrote:
> 
> > On 2013/01/02 22:44:16, I haz the power (commit-bot) wrote:
> >
> >> Change committed as 174880
> >>
> >
> > Note this was reverted in
>
https://codereview.chromium.**org/11734018/%3Chttps://codereview.chromium.org...>
> 
> 
> just on a branch...
> 

*phew*. I will now pull from trunk with comfort.

- Gavin

> >
> >
> >
>
https://chromiumcodereview.**appspot.com/11728003/%3Chttps://chromiumcoderevi...>
> >