cc: Remove map lookup from RenderSurfaceImpl::EffectTreeIndex

cc/layers/render_surface_impl.h

Index: cc/layers/render_surface_impl.h
diff --git a/cc/layers/render_surface_impl.h b/cc/layers/render_surface_impl.h
index 80c2c15fe73c27e9818eb92ae9df3c6ecbb4247f..6f024da9e8d432266df7e756264ac71f5171c527 100644
--- a/cc/layers/render_surface_impl.h
+++ b/cc/layers/render_surface_impl.h
@@ -151,6 +151,8 @@ class CC_EXPORT RenderSurfaceImpl {
 
   int TransformTreeIndex() const;
   int ClipTreeIndex() const;
+
+  void set_effect_tree_index(int index) { effect_tree_index_ = index; }
   int EffectTreeIndex() const;
 
  private:
@@ -163,6 +165,7 @@ class CC_EXPORT RenderSurfaceImpl {
 
   LayerTreeImpl* layer_tree_impl_;
   int stable_effect_id_;
+  int effect_tree_index_;
 
   // Container for properties that render surfaces need to compute before they
   // can be drawn.