Revert of [#7] Pass gfx structs by const ref (gfx::Size)

cc/output/direct_renderer.cc

Index: cc/output/direct_renderer.cc
diff --git a/cc/output/direct_renderer.cc b/cc/output/direct_renderer.cc
index 06e2afb0828c02a71f01bd4d179a7d7d792fe445..f90789d2145d8bce9c085c6c9df9b2b0fdcbfda1 100644
--- a/cc/output/direct_renderer.cc
+++ b/cc/output/direct_renderer.cc
@@ -83,7 +83,7 @@
 void DirectRenderer::InitializeViewport(DrawingFrame* frame,
                                         const gfx::Rect& draw_rect,
                                         const gfx::Rect& viewport_rect,
-                                        const gfx::Size& surface_size) {
+                                        gfx::Size surface_size) {
   bool flip_y = FlippedFramebuffer();
 
   DCHECK_GE(viewport_rect.x(), 0);