shill: cellular: Support Device.SetCarrier to allow UI-based CDMA/UMTS switch.

BUG=chromium-os:32472
TEST=Unit tests. Tested on device through 'dbus-send --system --print-reply
--dest=org.chromium.flimflam /device/wwan0
org.chromium.flimflam.Device.SetCarrier "string:Generic UMTS"' -- used Foo and
'Verizon Wireless' for the carrier too -- observed updated firmware through
'modem status' and logs, or Failure in case of Foo.

Change-Id: I330f916b6116a9ec9438f600d263c546a2b561ef
Reviewed-on: https://gerrit.chromium.org/gerrit/32389
Tested-by: Darin Petkov <petkov@chromium.org>
Reviewed-by: Ben Chan <benchan@chromium.org>
Commit-Ready: Darin Petkov <petkov@chromium.org>
diff --git a/mock_modem_gobi_proxy.cc b/mock_modem_gobi_proxy.cc
new file mode 100644
index 0000000..203110f
--- /dev/null
+++ b/mock_modem_gobi_proxy.cc
@@ -0,0 +1,13 @@
+// Copyright (c) 2012 The Chromium OS Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "shill/mock_modem_gobi_proxy.h"
+
+namespace shill {
+
+MockModemGobiProxy::MockModemGobiProxy() {}
+
+MockModemGobiProxy::~MockModemGobiProxy() {}
+
+}  // namespace shill