Let SysUI set wake-from-idle alarms with impunity

In an always-on display environment the device may go into doze, but
SysUI will still need to update the display on an ongoing basis.

Bug 36506772
Test: manual

Change-Id: I0b20ba7c352bac7c278f659f0e29496cc342d381
diff --git a/packages/SystemUI/AndroidManifest.xml b/packages/SystemUI/AndroidManifest.xml
index 55f32d7..983758b 100644
--- a/packages/SystemUI/AndroidManifest.xml
+++ b/packages/SystemUI/AndroidManifest.xml
@@ -24,6 +24,10 @@
 
     <protected-broadcast android:name="com.android.systemui.action.PLUGIN_CHANGED" />
 
+    <!-- SysUI must be the one to define this permission; its name is
+         referenced by the core OS. -->
+    <permission android:name="android.permission.systemui.IDENTITY"
+        android:protectionLevel="signature" />
 
     <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
     <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />