[#2] Pass gfx structs by const ref (gfx::Rect, gfx::RectF)

cc/base/math_util.cc

Index: cc/base/math_util.cc
diff --git a/cc/base/math_util.cc b/cc/base/math_util.cc
index 7a1bc1a8674287b6a581457fe1ffe53bfd31e816..0cc120d89094c818e72f6480711c6e3a5ed1e99a 100644
--- a/cc/base/math_util.cc
+++ b/cc/base/math_util.cc
@@ -102,7 +102,7 @@ static inline void AddVertexToClippedQuad(gfx::PointF new_vertex,
 }
 
 gfx::Rect MathUtil::MapClippedRect(const gfx::Transform& transform,
-                                   gfx::Rect src_rect) {
+                                   const gfx::Rect& src_rect) {
   return gfx::ToEnclosingRect(MapClippedRect(transform, gfx::RectF(src_rect)));
 }
 
@@ -521,7 +521,7 @@ scoped_ptr<base::Value> MathUtil::AsValue(gfx::SizeF s) {
   return res.PassAs<base::Value>();
 }
 
-scoped_ptr<base::Value> MathUtil::AsValue(gfx::Rect r) {
+scoped_ptr<base::Value> MathUtil::AsValue(const gfx::Rect& r) {
   scoped_ptr<base::ListValue> res(new base::ListValue());
   res->AppendInteger(r.x());
   res->AppendInteger(r.y());