shill: wimax: Listen to WiMaxManager.Device.StatusChanged signal.

Use the status signal to update the connection state of the WiMax
service appropriately. Also, make sure that WiMaxService is
disassociated from the carrier device if a connection can't be
initiated or if it's dropped.

BUG=chrome-os-partner:10010
TEST=unit tests
CQ-DEPEND=I29dcfe4915e6f2559d022c60353aa12358ef5966
CQ-DEPEND=I223eaf61894f74905c591e38590e5e0620d07be0

Change-Id: I5fe48f0cc84c066eb6a63dc5d347ac5f265b86b1
Reviewed-on: https://gerrit.chromium.org/gerrit/23879
Tested-by: Darin Petkov <petkov@chromium.org>
Reviewed-by: Paul Stewart <pstew@chromium.org>
Commit-Ready: Ben Chan <benchan@chromium.org>
diff --git a/mock_wimax_device_proxy.h b/mock_wimax_device_proxy.h
index 2b1412a..906a984 100644
--- a/mock_wimax_device_proxy.h
+++ b/mock_wimax_device_proxy.h
@@ -36,6 +36,8 @@
                                 int timeout));
   MOCK_METHOD1(set_networks_changed_callback,
                void(const NetworksChangedCallback &callback));
+  MOCK_METHOD1(set_status_changed_callback,
+               void(const StatusChangedCallback &callback));
   MOCK_METHOD1(Index, uint8(Error *error));
   MOCK_METHOD1(Name, std::string(Error *error));