Unexpected packets are observed after captive portal check. Due to the packets, modem can't fall-back to idle state (modem remained as active state).
It makes unnecessary power consumtion.
To prevent it, "close" option is added in sendHttpProbe()
Test: check socket close.
Change-Id: I5b6987071ad915081846504adbb209eb371fd1c3
urlConnection.setInstanceFollowRedirects(probeType == ValidationProbeEvent.PROBE_PAC);
urlConnection.setConnectTimeout(SOCKET_TIMEOUT_MS);
urlConnection.setReadTimeout(SOCKET_TIMEOUT_MS);
+ urlConnection.setRequestProperty("Connection", "close");
urlConnection.setUseCaches(false);
if (mCaptivePortalUserAgent != null) {
urlConnection.setRequestProperty("User-Agent", mCaptivePortalUserAgent);