Cleanup debug options

Bug: 18138852
Bug: 18065434
Change-Id: Ibb07b73b147c2a8b287fe8aee3f6624582f21b00
diff --git a/libs/hwui/Properties.h b/libs/hwui/Properties.h
index 7eb9a32..befed16 100644
--- a/libs/hwui/Properties.h
+++ b/libs/hwui/Properties.h
@@ -133,6 +133,15 @@
 #define PROPERTY_DEBUG_STENCIL_CLIP "debug.hwui.show_non_rect_clip"
 
 /**
+ * Turn on to draw dirty regions every other frame.
+ *
+ * Possible values:
+ * "true", to enable dirty regions debugging
+ * "false", to disable dirty regions debugging
+ */
+#define PROPERTY_DEBUG_SHOW_DIRTY_REGIONS "debug.hwui.show_dirty_regions"
+
+/**
  * Disables draw operation deferral if set to "true", forcing draw
  * commands to be issued to OpenGL in order, and processed in sequence
  * with state-manipulation canvas commands.