Updated (internal) API for IStreamSource to signal discontinuities

Change-Id: Idd4b9d8e7cec16b3e3c91c70e75144d42be30f96
related-to-bug: 5553055
diff --git a/media/libmedia/IStreamSource.cpp b/media/libmedia/IStreamSource.cpp
index b311f35..078be94 100644
--- a/media/libmedia/IStreamSource.cpp
+++ b/media/libmedia/IStreamSource.cpp
@@ -30,7 +30,7 @@
 const char *const IStreamListener::kKeyResumeAtPTS = "resume-at-PTS";
 
 // static
-const char *const IStreamListener::kKeyFormatChange = "format-change";
+const char *const IStreamListener::kKeyDiscontinuityMask = "discontinuity-mask";
 
 enum {
     // IStreamSource