Don't use IO thread to talk to dbus.  dbus uses glib message loop which is driven by UI thread.  It is correct to use UI thread to talk to dbus (for now)  It's not proven but this may be a source of obscure race bugs, or at least, we can exclude this from the potential source.
Don't use IO thread to talk to dbus.
 dbus uses glib message loop which is driven by UI thread.
 It is correct to use UI thread to talk to dbus (for now)
 It's not proven but this may be a source of obscure race bugs, or at least, we can exclude this from the potential source.

BUG=chromium-os:7490.
TEST=screen locker works as before.

Review URL: http://codereview.chromium.org/4024005

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@63926 0039d316-1c4b-4281-b951-d872f2087c98

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