Add ResetModem method and call it once non_cellular activation is done.

chromeos/dbus/mock_shill_device_client.h

Index: chromeos/dbus/mock_shill_device_client.h
diff --git a/chromeos/dbus/mock_shill_device_client.h b/chromeos/dbus/mock_shill_device_client.h
index 26b80327254df7e71401308172caa3f9a9f2e583..3f2a2db8f7262ff332a4b45969856be707378a10 100644
--- a/chromeos/dbus/mock_shill_device_client.h
+++ b/chromeos/dbus/mock_shill_device_client.h
@@ -71,6 +71,9 @@ class MockShillDeviceClient : public ShillDeviceClient {
                                 const std::string& carrier,
                                 const base::Closure& callback,
                                 const ErrorCallback& error_callback));
+  MOCK_METHOD3(Reset, void(const dbus::ObjectPath& device_path,
+                           const base::Closure& callback,
+                           const ErrorCallback& error_callback));
   MOCK_METHOD0(GetTestInterface, TestInterface*());
 };