cc: Move blend_mode to the effect tree

cc/layers/layer.h

 // Copyright 2010 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CC_LAYERS_LAYER_H_
 #define CC_LAYERS_LAYER_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 132 matching lines @@
   SkXfermode::Mode blend_mode() const { return inputs_.blend_mode; }
 
   void set_draw_blend_mode(SkXfermode::Mode blend_mode) {
     if (draw_blend_mode_ == blend_mode)
       return;
     draw_blend_mode_ = blend_mode;
     SetNeedsPushProperties();
   }
   SkXfermode::Mode draw_blend_mode() const { return draw_blend_mode_; }
 
-  bool uses_default_blend_mode() const {
-    return inputs_.blend_mode == SkXfermode::kSrcOver_Mode;
-  }
-
   // A layer is root for an isolated group when it and all its descendants are
   // drawn over a black and fully transparent background, creating an isolated
   // group. It should be used along with SetBlendMode(), in order to restrict
   // layers within the group to blend with layers outside this group.
   void SetIsRootForIsolatedGroup(bool root);
   bool is_root_for_isolated_group() const {
     return inputs_.is_root_for_isolated_group;
   }
 
   void SetFilters(const FilterOperations& filters);
@@ skipping 558 matching lines @@
   // These all act like draw properties, so don't need push properties.
   gfx::Rect visible_layer_rect_;
   size_t num_unclipped_descendants_;
 
   DISALLOW_COPY_AND_ASSIGN(Layer);
 };
 
 }  // namespace cc
 
 #endif  // CC_LAYERS_LAYER_H_