Enable system service to notify device owners about pending update

Create a DevicePolicyManager API which can be used by OTA subsystem
to tell device owners about pending updates. Device owners will get
a callback from its DeviceAdminReceiver when the update service sends
out such notifications.

Bug: 20213644
Change-Id: Ifcc755655e4f441980cf77d76175a046112ca9ae
diff --git a/core/res/AndroidManifest.xml b/core/res/AndroidManifest.xml
index fa5e4ad..62685a1 100644
--- a/core/res/AndroidManifest.xml
+++ b/core/res/AndroidManifest.xml
@@ -1116,6 +1116,11 @@
     <permission android:name="android.permission.ACCESS_PDB_STATE"
         android:protectionLevel="signature" />
 
+    <!-- @hide Allows system update service to notify device owner about pending updates.
+   <p>Not for use by third-party applications. -->
+    <permission android:name="android.permission.NOTIFY_PENDING_SYSTEM_UPDATE"
+        android:protectionLevel="signatureOrSystem" />
+
     <!-- =========================================== -->
     <!-- Permissions associated with camera and image capture -->
     <!-- =========================================== -->