mix-blend-mode implementation for accelerated layers

cc/layers/layer.h

Index: cc/layers/layer.h
diff --git a/cc/layers/layer.h b/cc/layers/layer.h
index 6f391ac863e27149825f4b66a188b8a81cce26d3..4cc7f5691415594b81e9257665edb76f7358d2ae 100644
--- a/cc/layers/layer.h
+++ b/cc/layers/layer.h
@@ -122,6 +122,18 @@ class CC_EXPORT Layer : public base::RefCounted<Layer>,
   bool OpacityIsAnimating() const;
   virtual bool OpacityCanAnimateOnImplThread() const;
 
+  void SetBlendMode(SkXfermode::Mode blend_mode);
+  SkXfermode::Mode blend_mode() const { return blend_mode_; }
+
+  bool uses_default_blend_mode() const {
+    return blend_mode_ == SkXfermode::kSrcOver_Mode;
+  }
+
+  void SetIsRootForIsolatedGroup(bool root);
+  bool is_root_for_isolated_group() const {
+    return is_root_for_isolated_group_;
+  }
+
   void SetFilters(const FilterOperations& filters);
   const FilterOperations& filters() const { return filters_; }
   bool FilterIsAnimating() const;
@@ -544,6 +556,8 @@ class CC_EXPORT Layer : public base::RefCounted<Layer>,
   SkColor background_color_;
   CompositingReasons compositing_reasons_;
   float opacity_;
+  SkXfermode::Mode blend_mode_;
+  bool is_root_for_isolated_group_;
   FilterOperations filters_;
   FilterOperations background_filters_;
   float anchor_point_z_;