Add an Ethernet EAP policy.

This is the last change required to enable the Ethernet EAP policy on ChromeOS.

BUG=126870
(For preferences_browsertest.cc)
TBR=nkostylev@chromium.org

Review URL: https://codereview.chromium.org/23451044

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226444 0039d316-1c4b-4281-b951-d872f2087c98
Create ModeIndicatorController

This class is a controller of ModeIndicatorWidget.

BUG=177765

Review URL: https://codereview.chromium.org/25670002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226445 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 226445