Revert of Perform BSP polygon splitting and orientation selection in a single step.

cc/quads/draw_polygon.h

Index: cc/quads/draw_polygon.h
diff --git a/cc/quads/draw_polygon.h b/cc/quads/draw_polygon.h
index 2dc642cde3195cd8beb47c74b72476cfb9ba1a5f..b3bde398c5556533d80deba71f0c030f64e8be30 100644
--- a/cc/quads/draw_polygon.h
+++ b/cc/quads/draw_polygon.h
@@ -40,11 +40,14 @@
   // Split will only return true if it determines that we got back 2
   // intersection points. Only when it returns true will front and back both be
   // valid new polygons that are on opposite sides of the splitting plane.
-  void SplitPolygon(std::unique_ptr<DrawPolygon> polygon,
-                    std::unique_ptr<DrawPolygon>* front,
-                    std::unique_ptr<DrawPolygon>* back,
-                    bool* is_coplanar) const;
+  bool Split(const DrawPolygon& splitter,
+             std::unique_ptr<DrawPolygon>* front,
+             std::unique_ptr<DrawPolygon>* back);
   float SignedPointDistance(const gfx::Point3F& point) const;
+  // Checks polygon a against polygon b and returns which side it lies on, or
+  // whether it crosses (necessitating a split in the BSP tree).
+  static BspCompareResult SideCompare(const DrawPolygon& a,
+                                      const DrawPolygon& b);
   void ToQuads2D(std::vector<gfx::QuadF>* quads) const;
   void TransformToScreenSpace(const gfx::Transform& transform);
   void TransformToLayerSpace(const gfx::Transform& inverse_transform);