Reland 238671 "Added net::NetworkInterface::interface_index."

net_unittests still failed after reverting the original CL, so
it obviously wasn't the cause of the failures.

> Revert 238671 "Added net::NetworkInterface::interface_index."
> 
> Speculative revert to see if it fixes the issues with net_unittests
> on WinXP: http://build.chromium.org/p/chromium.win/builders/XP%20Tests%20%282%29/builds/32133/steps/net_unittests/logs/stdio
> 
> > Added net::NetworkInterface::interface_index.
> > Not implemented for Android.
> > 
> > BUG=319068
> > 
> > Review URL: https://codereview.chromium.org/100703002
> 
> TBR=vitalybuka@chromium.org
> 
> Review URL: https://codereview.chromium.org/101403004

TBR=dubroy@chromium.org

Review URL: https://codereview.chromium.org/105053002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@238715 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 238715