Add drop shadows.

Change-Id: Ic6a72409d4785968d1fbdff229f17ee5c00b240b
diff --git a/libs/hwui/Properties.h b/libs/hwui/Properties.h
index 915b0be..7514b6f 100644
--- a/libs/hwui/Properties.h
+++ b/libs/hwui/Properties.h
@@ -27,6 +27,7 @@
 #define PROPERTY_LAYER_CACHE_SIZE "ro.hwui.layer_cache_size"
 #define PROPERTY_GRADIENT_CACHE_SIZE "ro.hwui.gradient_cache_size"
 #define PROPERTY_PATH_CACHE_SIZE "ro.hwui.path_cache_size"
+#define PROPERTY_DROP_SHADOW_CACHE_SIZE "ro.hwui.drop_shadow_cache_size"
 
 // These properties are defined in pixels
 #define PROPERTY_TEXT_CACHE_WIDTH "ro.hwui.text_cache_width"