StagefrightMetadataRetriever: handle error returned from convertMetaDataToMessage().

Bug: 23680780
Change-Id: I09dbbf95b2c874b9760938646e48a7ed543f1577
diff --git a/media/libstagefright/StagefrightMetadataRetriever.cpp b/media/libstagefright/StagefrightMetadataRetriever.cpp
index 7c554db..e37e909 100644
--- a/media/libstagefright/StagefrightMetadataRetriever.cpp
+++ b/media/libstagefright/StagefrightMetadataRetriever.cpp
@@ -146,7 +146,10 @@
     sp<MetaData> format = source->getFormat();
 
     sp<AMessage> videoFormat;
-    convertMetaDataToMessage(trackMeta, &videoFormat);
+    if (convertMetaDataToMessage(trackMeta, &videoFormat) != OK) {
+        ALOGW("Failed to convert meta data to message");
+        return NULL;
+    }
 
     // TODO: Use Flexible color instead
     videoFormat->setInt32("color-format", OMX_COLOR_FormatYUV420Planar);