[#4] Pass gfx structs by const ref (gfx::PointF)

cc/layers/layer_impl.h

Index: cc/layers/layer_impl.h
diff --git a/cc/layers/layer_impl.h b/cc/layers/layer_impl.h
index d124457c14a59ea576a9d5088c1f733809893270..d522acbc8b45f0ad5d86e16a3321af3cd40c7d9f 100644
--- a/cc/layers/layer_impl.h
+++ b/cc/layers/layer_impl.h
@@ -188,7 +188,7 @@ class CC_EXPORT LayerImpl : public LayerAnimationValueObserver,
   bool force_render_surface() const { return force_render_surface_; }
   void SetForceRenderSurface(bool force) { force_render_surface_ = force; }
 
-  void SetAnchorPoint(gfx::PointF anchor_point);
+  void SetAnchorPoint(const gfx::PointF& anchor_point);
   gfx::PointF anchor_point() const { return anchor_point_; }
 
   void SetAnchorPointZ(float anchor_point_z);
@@ -232,7 +232,7 @@ class CC_EXPORT LayerImpl : public LayerAnimationValueObserver,
     return is_root_for_isolated_group_;
   }
 
-  void SetPosition(gfx::PointF position);
+  void SetPosition(const gfx::PointF& position);
   gfx::PointF position() const { return position_; }
 
   void SetIsContainerForFixedPositionLayers(bool container) {
@@ -435,7 +435,7 @@ class CC_EXPORT LayerImpl : public LayerAnimationValueObserver,
   bool DrawCheckerboardForMissingTiles() const;
 
   InputHandler::ScrollStatus TryScroll(
-      gfx::PointF screen_space_point,
+      const gfx::PointF& screen_space_point,
       InputHandler::ScrollInputType type) const;
 
   void SetDoubleSided(bool double_sided);