cc: Stop converting Rect to QuadF to map to an enclosed rect.

cc/base/math_util.h

Index: cc/base/math_util.h
diff --git a/cc/base/math_util.h b/cc/base/math_util.h
index 486a654a5e49a76e9483f350760a61b500dc9732..eaaf9249568fffeaa0bed1fd01d2760a1811897a 100644
--- a/cc/base/math_util.h
+++ b/cc/base/math_util.h
@@ -115,6 +115,12 @@ class CC_EXPORT MathUtil {
   static gfx::RectF ProjectClippedRect(const gfx::Transform& transform,
                                        const gfx::RectF& rect);
 
+  // This function is only valid when the transform preserves 2d axis
+  // alignment and the resulting rect will not be clipped.
+  static gfx::Rect MapEnclosedRectWith2dAxisAlignedTransform(
+      const gfx::Transform& transform,
+      const gfx::Rect& rect);
+
   // Returns an array of vertices that represent the clipped polygon. After
   // returning, indexes from 0 to num_vertices_in_clipped_quad are valid in the
   // clipped_quad array. Note that num_vertices_in_clipped_quad may be zero,