Add private enums.

This is cherry picked from ag/1380640 and ag/1483972.

Test: wayland_service builds.

Change-Id: I09eb7d8837c639a668a18545ab23cab2d7c6b751
diff --git a/gralloc_drm_handle.h b/gralloc_drm_handle.h
index 3474d3c..fd79cce 100644
--- a/gralloc_drm_handle.h
+++ b/gralloc_drm_handle.h
@@ -81,6 +81,19 @@
 	return handle;
 }
 
+/*
+ * The functions supported by gralloc_drm's temporary private API are listed
+ * below. Use of these functions is highly discouraged and should only be
+ * reserved for cases where no alternative to get same information (such as
+ * querying ANativeWindow) exists.
+ */
+enum {
+  GRALLOC_DRM_GET_STRIDE,
+  GRALLOC_DRM_GET_FORMAT,
+  GRALLOC_DRM_GET_DIMENSIONS,
+  GRALLOC_DRM_GET_BACKING_STORE,
+};
+
 #ifdef __cplusplus
 }
 #endif