Add histogram for consumer use of account whitelisting

We know that enterprise managed Chrome OS devices often
allow accounts from only their domain to be used on the
device. We have functionality to allow the Owner of a
consumer device to do similar account whitelisting.
We'd like to track consumer usage of this feature, so add
a histogram for it.

BUG=chromium:345352
TEST=build the browser

Review URL: https://codereview.chromium.org/193143002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@256708 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 256708
Relanding https://codereview.chromium.org/159353002/ after some minor modifications. Fixing tests mainly.

It got reverted due to ASAN failures in http://build.chromium.org/p/chromium.memory/buildstatus?builder=Linux%20ASan%2BLSan%20Tests%20%282%29&number=396

Original CL description:
This CL adds methods to manipulate RTP header extension, particularly
AbsoulteSendTime extension. If there is matching extension ID present
in RTP packet, we will update with the current time.

TBR=sergeyu@chromium.org

Review URL: https://codereview.chromium.org/197713005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@256709 0039d316-1c4b-4281-b951-d872f2087c98
cros: No enrollment after enabling consumer kiosk autolaunch

BUG=347344

Review URL: https://codereview.chromium.org/193063002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@256710 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 256710