message: Add TODO regarding use of GraphTopologyView
diff: @@ -377,6 +377,8 @@ struct NodeTypeIdEdge {
  NodeTypeId dst;
  };
  +// TODO(benbarsdell): Investigate whether the existing GraphTopologyView can be
  +// used instead of this modified version.
  // This is just like GraphTopologyView but with (NodeDef, TypeAttrId) pairs as
  // the vertices instead of just NodeDef.
  // For example, if node A has output A:0 with TypeAttrId 'T', and node B has
  