Add support for secure system overlays.

Manual merge from Gingerbread.

This change adds a new window type for secure system overlays
created by the system itself from non-secure system overlays that
might be created by applications that have the system alert permission.
Secure views ignore the presence of secure system overlays.

Bug: 3098519
Change-Id: Id876736fd8bf332ff9a5428bde59f5268aa49c3a
diff --git a/services/java/com/android/server/LoadAverageService.java b/services/java/com/android/server/LoadAverageService.java
index 0d86429..b6baadb 100644
--- a/services/java/com/android/server/LoadAverageService.java
+++ b/services/java/com/android/server/LoadAverageService.java
@@ -272,7 +272,7 @@
         WindowManager.LayoutParams params = new WindowManager.LayoutParams(
             WindowManager.LayoutParams.WRAP_CONTENT,
             WindowManager.LayoutParams.WRAP_CONTENT,
-            WindowManager.LayoutParams.TYPE_SYSTEM_OVERLAY,
+            WindowManager.LayoutParams.TYPE_SECURE_SYSTEM_OVERLAY,
             WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE|
             WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE,
             PixelFormat.TRANSLUCENT);