Allowed to construct a dbus::BusConnection object with NULL g_connection

Allowed to construct a dbus::BusConnection object with NULL g_connection (just like dbus::Proxy) to fix TODO in the GetPrivateConnection function.

BUG=none

[Zachary Kuznia, 2010-06-23 06:27:45]

http://codereview.chromium.org/2842019/diff/1/2
File chromeos/dbus/dbus.cc (right):

http://codereview.chromium.org/2842019/diff/1/2#newcode74
chromeos/dbus/dbus.cc:74: ::dbus_error_free(&error);
I've seen this case hit, too.  Could you add a similar null return here?

It would probably be useful to output the error message to the log here as well.

[Yusuke Sato, 2010-06-23 06:52:08]

http://codereview.chromium.org/2842019/diff/1/2
File chromeos/dbus/dbus.cc (right):

http://codereview.chromium.org/2842019/diff/1/2#newcode74
chromeos/dbus/dbus.cc:74: ::dbus_error_free(&error);
On 2010/06/23 06:27:45, Zachary Kuznia wrote:
> I've seen this case hit, too.  Could you add a similar null return here?
> 
> It would probably be useful to output the error message to the log here as
well.

Done.

[Zachary Kuznia, 2010-06-23 06:53:43]

LGTM