Add support for secure system overlays.  (DO NOT MERGE)

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: I8f8398f4fdeb0469e5d71124c21bedf121bd8c07
diff --git a/libs/ui/InputDispatcher.cpp b/libs/ui/InputDispatcher.cpp
index 6ba19d7..4112328 100644
--- a/libs/ui/InputDispatcher.cpp
+++ b/libs/ui/InputDispatcher.cpp
@@ -149,7 +149,8 @@
 
 bool InputWindow::isTrustedOverlay() const {
     return layoutParamsType == TYPE_INPUT_METHOD
-            || layoutParamsType == TYPE_INPUT_METHOD_DIALOG;
+            || layoutParamsType == TYPE_INPUT_METHOD_DIALOG
+            || layoutParamsType == TYPE_SECURE_SYSTEM_OVERLAY;
 }
 
 
@@ -1350,7 +1351,7 @@
         target.flags = 0;
         target.xOffset = 0;
         target.yOffset = 0;
-        target.windowType = InputWindow::TYPE_SYSTEM_OVERLAY;
+        target.windowType = -1;
     }
 }