Show ****** in wifi passphrase field
Shill does not send the passphrase to Chrome for security reasons, so
show ****** in the passphrase field when configuring wifi if the service
is Connectable. (Sometimes when a connection fails we do not know why
it failed and so we show the configure dialog in case it is an error in
the configuration).
BUG=264819
Review URL: https://chromiumcodereview.appspot.com/
23522013
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@221491 0039d316-1c4b-4281-b951-d872f2087c98