SELinux policies for /data/preloads directory

A new directory is created in user data partition that contains preloaded
content such as a retail mode demo video and pre-loaded APKs.

The new directory is writable/deletable by system server. It can only be
readable (including directory list) by privileged or platform apps

Bug: 28855287
Change-Id: I3816cd3a1ed5b9a030965698a66265057214f037
diff --git a/file_contexts b/file_contexts
index c4f8f6a..062b929 100644
--- a/file_contexts
+++ b/file_contexts
@@ -260,6 +260,7 @@
 /data/mediadrm(/.*)?	u:object_r:media_data_file:s0
 /data/nativetest(/.*)?	u:object_r:nativetest_data_file:s0
 /data/property(/.*)?	u:object_r:property_data_file:s0
+/data/preloads(/.*)?	u:object_r:preloads_data_file:s0
 
 # Misc data
 /data/misc/adb(/.*)?            u:object_r:adb_keys_file:s0