cellular: Properly propagate args from test environment to pseudomm

Also in this CL is code to use DBus bus in test environment for
pseudomodem.

BUG=chromium:411045
TEST=Run network_3GSmokeTest.pseudomodem and check net.log and verify
that pseudomodem creates a 3GPP modem and a CDMA modem.

Change-Id: I2dd08be0a721b4fe5d128603ac1f32251cb5e1dc
Reviewed-on: https://chromium-review.googlesource.com/216522
Reviewed-by: Prathmesh Prabhu <pprabhu@chromium.org>
Commit-Queue: Thieu Le <thieule@chromium.org>
Tested-by: Thieu Le <thieule@chromium.org>
diff --git a/client/cros/cellular/test_environment.py b/client/cros/cellular/test_environment.py
index 76c6bcc..1846ee0 100644
--- a/client/cros/cellular/test_environment.py
+++ b/client/cros/cellular/test_environment.py
@@ -228,7 +228,8 @@
         """
         super(CellularPseudoMMTestEnvironment, self).__init__(**kwargs)
         self._context_managers.append(
-                pseudomodem_context.PseudoModemManagerContext(*pseudomm_args))
+                pseudomodem_context.PseudoModemManagerContext(
+                        True, bus=self.bus, *pseudomm_args))
 
 
 class CellularWardModemTestEnvironment(CellularTestEnvironment):