Create new mediaprovider_app domain.

This is a domain for the MediaProvider mainline module. The
MediaProvider process is responsible for managing external storage, and
as such should be able to have full read/write access to it. It also
hosts a FUSE filesystem that allows other apps to access said storage in
a safe way. Finally, it needs to call some ioctl's to set project quota
on the lower filesystem correctly.

Bug: 141595441
Test: builds, mediaprovider module gets the correct domain
Change-Id: I0d705148774a1bbb59c927e267a484cb5c44f548
diff --git a/private/app_neverallows.te b/private/app_neverallows.te
index 677b9e2..f08f516 100644
--- a/private/app_neverallows.te
+++ b/private/app_neverallows.te
@@ -6,6 +6,7 @@
   ephemeral_app
   isolated_app
   mediaprovider
+  mediaprovider_app
   untrusted_app
   untrusted_app_25
   untrusted_app_27
@@ -145,8 +146,8 @@
   ')
 }:dir_file_class_set { create unlink };
 
-# No untrusted component should be touching /dev/fuse
-neverallow all_untrusted_apps fuse_device:chr_file *;
+# No untrusted component except mediaprovider_app should be touching /dev/fuse
+neverallow { all_untrusted_apps -mediaprovider_app } fuse_device:chr_file *;
 
 # Do not allow untrusted apps to directly open the tun_device
 neverallow all_untrusted_apps tun_device:chr_file open;