Apply the bad flags infobar to some more security-relevant flags

BUG=343921

Review URL: https://codereview.chromium.org/178803004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@255314 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 255314
Adds TODO comment on the timing of removing the disable-ignore-autocomplete-off
switch and field trial.

BUG=346708

Review URL: https://codereview.chromium.org/183923021

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@255315 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 255315
Add LogoutConfirmationController to show LogoutConfirmationDialogs

LogoutButtonTray uses and owns LogoutConfirmationDialogView, a dialog that
asks the user to confirm or deny logout. This CL generalizes the dialog
and moves its ownership to a LogoutConfirmationController accessible via
ash::Shell, allowing other classes to show the same dialog.

BUG=278247
TEST=Updated unit tests

Review URL: https://codereview.chromium.org/178183005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@255316 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 255316