Clarify settings UI in multi-profiles mode

Adds bubble buttons to indicate which settings are shared.

When signed in as a secondary user (i.e., added to a multi-profile session),
a banner should be display. The "Internet connection" header should show a
shared icon. Owner-controlled settings should show the owner icon.
"Require password to wake from sleep" is a special case.

This also fixes a bug where controlled settings on managed devices should say
they are controlled by policy, but instead say the (non-existent) owner controls
them.

For details, see PRD with additional links at bottom:
https://docs.google.com/a/google.com/document/d/1G09Mql1TtVFA4qhb7hlt4u2crBv6_fhrZMf40Yo--lc

BUG=326354
R=dbeam@chromium.org, stevenjb@chromium.org, oshima@chromium.org

Review URL: https://codereview.chromium.org/152143009

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@251302 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 251302