[#3] Pass gfx structs by const ref (gfx::SizeF)

cc/output/render_surface_filters.h

Index: cc/output/render_surface_filters.h
diff --git a/cc/output/render_surface_filters.h b/cc/output/render_surface_filters.h
index 09d0f732a03b795fde5ef4cbc36cac57152161a3..42b6e451501412ed46bbedd28f444eb7b3743884 100644
--- a/cc/output/render_surface_filters.h
+++ b/cc/output/render_surface_filters.h
@@ -26,13 +26,13 @@ class CC_EXPORT RenderSurfaceFilters {
  public:
   static SkBitmap Apply(const FilterOperations& filters,
                         unsigned texture_id,
-                        gfx::SizeF size,
+                        const gfx::SizeF& size,
                         GrContext* gr_context);
   static FilterOperations Optimize(const FilterOperations& filters);
 
   static skia::RefPtr<SkImageFilter> BuildImageFilter(
       const FilterOperations& filters,
-      gfx::SizeF size);
+      const gfx::SizeF& size);
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(RenderSurfaceFilters);