Replace kEmptyString wth OnceInit initialized string*

Replace kEmptyString wth OnceInit initialized string*

This removes the global constructor call for std::string kEmptyString. 

This is an application with minor changes of b/7549760
from the internal version protobuf.

[scottmg, 2014-02-13 21:43:59]

I'm not sure if you want this applied, but we would like to get rid of
kEmptyString (and all global constructors) in chromium. This one in particular
is causing some CRT initialization ordering problems.

[xiaofeng, 2014-02-13 22:10:39]

LGTM

Committed to svn as r517

[scottmg, 2014-02-13 22:35:30]

Thanks!


On Thu, Feb 13, 2014 at 2:10 PM, <xiaofeng@google.com> wrote:

> LGTM
>
> Committed to svn as r517
>
> https://codereview.appspot.com/63480043/
>