Lock down MANAGE_DOCUMENTS permission.

MANAGE_DOCUMENTS is a very broad permission, since it allows full
access to all DocumentsProviders.  DocumentsUI should really be the
only app holding this permission; everyone else should rely on Uri
permission grants for access.

Bug: 12958298
Change-Id: I1def48a4ea1814e031fc8513c3cd051d764cd7f8
diff --git a/core/res/AndroidManifest.xml b/core/res/AndroidManifest.xml
index daff390..ca31109 100644
--- a/core/res/AndroidManifest.xml
+++ b/core/res/AndroidManifest.xml
@@ -1192,7 +1192,7 @@
         android:permissionGroup="android.permission-group.STORAGE"
         android:label="@string/permlab_manageDocs"
         android:description="@string/permdesc_manageDocs"
-        android:protectionLevel="signature|system" />
+        android:protectionLevel="signature" />
 
     <!-- ================================== -->
     <!-- Permissions for screenlock         -->