HTTPLiveSource: NULL check in getFormat

Bug: 18297916
Change-Id: I14c5de8d28202ee1b68e369d33e01bd26dbe968d
diff --git a/media/libmediaplayerservice/nuplayer/HTTPLiveSource.cpp b/media/libmediaplayerservice/nuplayer/HTTPLiveSource.cpp
index a003c81..02e9caf 100644
--- a/media/libmediaplayerservice/nuplayer/HTTPLiveSource.cpp
+++ b/media/libmediaplayerservice/nuplayer/HTTPLiveSource.cpp
@@ -98,6 +98,10 @@
 }
 
 sp<AMessage> NuPlayer::HTTPLiveSource::getFormat(bool audio) {
+    if (mLiveSession == NULL) {
+        return NULL;
+    }
+
     sp<AMessage> format;
     status_t err = mLiveSession->getStreamFormat(
             audio ? LiveSession::STREAMTYPE_AUDIO