[DO NOT MERGE] Add CellBroadcastService and related permissions

CellBroadcastService is bound to by the platform to handle cell
broadcasts.

Bug: 135956699
Test: manual
Change-Id: I865c09d6d246779b706c06371df685d415618699
diff --git a/core/res/AndroidManifest.xml b/core/res/AndroidManifest.xml
index 6b4c757..dee53db 100644
--- a/core/res/AndroidManifest.xml
+++ b/core/res/AndroidManifest.xml
@@ -772,6 +772,18 @@
         android:permissionFlags="hardRestricted"
         android:protectionLevel="dangerous" />
 
+    <!-- @SystemApi @TestApi Allows an application to forward cell broadcast messages to the cell
+         broadcast module. This is required in order to bind to the cell broadcast service, and
+         ensures that only the system can forward messages to it.
+
+         <p>Protection level: signature
+
+         @hide -->
+    <permission android:name="android.permission.BIND_CELL_BROADCAST_SERVICE"
+        android:label="@string/permlab_bindCellBroadcastService"
+        android:description="@string/permdesc_bindCellBroadcastService"
+        android:protectionLevel="signature" />
+
     <!-- @SystemApi @TestApi Allows an application to read previously received cell broadcast
          messages and to register a content observer to get notifications when
          a cell broadcast has been received and added to the database. For