Add support for a new developer setting: overdraw debugging

Change-Id: I350ba4486577c3289f82c20938f7a35138778727
diff --git a/libs/hwui/Properties.h b/libs/hwui/Properties.h
index 0e3268e..31e60e44 100644
--- a/libs/hwui/Properties.h
+++ b/libs/hwui/Properties.h
@@ -37,7 +37,7 @@
 // Defines the size in bits of the stencil buffer
 // Note: Only 1 bit is required for clipping but more bits are required
 // to properly implement the winding fill rule when rasterizing paths
-#define STENCIL_BUFFER_SIZE 0
+#define STENCIL_BUFFER_SIZE 8
 
 /**
  * Debug level for app developers. The value is a numeric value defined
@@ -56,11 +56,17 @@
 };
 
 /**
- * Used to enable/disbale layers update debugging. The accepted values are
+ * Used to enable/disable layers update debugging. The accepted values are
  * "true" and "false". The default value is "false".
  */
 #define PROPERTY_DEBUG_LAYERS_UPDATES "debug.hwui.show_layers_updates"
 
+/**
+ * Used to enable/disable overdraw debugging. The accepted values are
+ * "true" and "false". The default value is "false".
+ */
+#define PROPERTY_DEBUG_OVERDRAW "debug.hwui.show_overdraw"
+
 // These properties are defined in mega-bytes
 #define PROPERTY_TEXTURE_CACHE_SIZE "ro.hwui.texture_cache_size"
 #define PROPERTY_LAYER_CACHE_SIZE "ro.hwui.layer_cache_size"