cc: Move blend_mode to the effect tree

cc/trees/effect_node.h

Index: cc/trees/effect_node.h
diff --git a/cc/trees/effect_node.h b/cc/trees/effect_node.h
index edb3a072600ab8c20051b2654f5418a0359ae571..b4f722ae50811f90d62db3791d9515e7b04f42ef 100644
--- a/cc/trees/effect_node.h
+++ b/cc/trees/effect_node.h
@@ -7,6 +7,7 @@
 
 #include "cc/base/cc_export.h"
 #include "cc/output/filter_operations.h"
+#include "third_party/skia/include/core/SkXfermode.h"
 
 namespace base {
 namespace trace_event {
@@ -36,6 +37,8 @@ struct CC_EXPORT EffectNode {
   FilterOperations filters;
   FilterOperations background_filters;
 
+  SkXfermode::Mode blend_mode;
+
   gfx::Vector2dF surface_contents_scale;
 
   bool has_render_surface;