shill: implement manager.RequestScan (for WiFi only)

BUG=chromium-os:19831
TEST=unittests, WiFiManager/000_SSID_Length_Limit

note that 000_SSID_Length_Limit does not pass yet,
because we don't do IP configuration yet. but it
does get scan results.

Change-Id: I8993b3c646eda705271d1f7ad7d7341c692ae06b
Reviewed-on: http://gerrit.chromium.org/gerrit/7407
Reviewed-by: mukesh agrawal <quiche@chromium.org>
Tested-by: mukesh agrawal <quiche@chromium.org>
diff --git a/mock_manager.h b/mock_manager.h
index 21da55e..bc3280e 100644
--- a/mock_manager.h
+++ b/mock_manager.h
@@ -21,6 +21,7 @@
 
   MOCK_METHOD0(device_info, DeviceInfo*(void));
   MOCK_METHOD0(store, PropertyStore*(void));
+  MOCK_METHOD1(RegisterService, void(const ServiceRefPtr &to_manage));
   MOCK_METHOD1(UpdateService, void(const ServiceConstRefPtr &to_update));
 
  private: