MediaCas: add MediaCasService

This CL adds API only without implementation.

bug: 22804304
Change-Id: Ibb5a29cc616ec0af81957b2bfe1419c482591753
diff --git a/services/mediadrm/Android.mk b/services/mediadrm/Android.mk
index e72236d..87fddd4 100644
--- a/services/mediadrm/Android.mk
+++ b/services/mediadrm/Android.mk
@@ -17,6 +17,7 @@
 include $(CLEAR_VARS)
 
 LOCAL_SRC_FILES:= \
+    MediaCasService.cpp \
     MediaDrmService.cpp \
     main_mediadrmserver.cpp