MediaCas: add MediaCasService

This CL adds API only without implementation.

bug: 22804304
Change-Id: Ibb5a29cc616ec0af81957b2bfe1419c482591753
diff --git a/media/libmedia/Android.mk b/media/libmedia/Android.mk
index 6c6c369..eac532b 100644
--- a/media/libmedia/Android.mk
+++ b/media/libmedia/Android.mk
@@ -60,10 +60,10 @@
         libui liblog libcutils libutils libbinder libsonivox libicuuc libicui18n libexpat \
         libcamera_client libstagefright_foundation \
         libgui libdl libaudioutils libaudioclient \
-        libmedia_helper \
+        libmedia_helper libmediadrm \
         libhidlbase \
 
-LOCAL_EXPORT_SHARED_LIBRARY_HEADERS := libbinder libsonivox
+LOCAL_EXPORT_SHARED_LIBRARY_HEADERS := libbinder libsonivox libmediadrm
 
 # for memory heap analysis
 LOCAL_STATIC_LIBRARIES := libc_malloc_debug_backtrace libc_logging