Pass gfx structs by const ref (gfx::Vector2d/F)

Pass gfx structs by const ref (gfx::Vector2d/F)
Avoid unneccessary copy of structures gfx::Vector2d/F by passing them
by const ref rather than value. Any struct of size > 4 bytes should be
passed by const ref. Passing by ref for these structs is faster than
passing by value, especially when invoking function has multiple
parameters.

BUG=159273

Review URL: https://codereview.chromium.org/1112813003

Cr-Commit-Position: refs/heads/master@{#328104}

2 files changed, 2 insertions, 2 deletions

diff --git a/ui/compositor/layer.cc b/ui/compositor/layer.cc
index ebafff0..f88557c 100644
--- a/ui/compositor/layer.cc
+++ b/ui/compositor/layer.cc
@@ -248,7 +248,7 @@ void Layer::SetBounds(const gfx::Rect& bounds) {
   GetAnimator()->SetBounds(bounds);
 }
 
-void Layer::SetSubpixelPositionOffset(const gfx::Vector2dF offset) {
+void Layer::SetSubpixelPositionOffset(const gfx::Vector2dF& offset) {
   subpixel_position_offset_ = offset;
   RecomputePosition();
 }
diff --git a/ui/compositor/layer.h b/ui/compositor/layer.h
index 4180034..571bdbf 100644
--- a/ui/compositor/layer.h
+++ b/ui/compositor/layer.h
@@ -151,7 +151,7 @@ class COMPOSITOR_EXPORT Layer
 
   // The offset from our parent (stored in bounds.origin()) is an integer but we
   // may need to be at a fractional pixel offset to align properly on screen.
-  void SetSubpixelPositionOffset(const gfx::Vector2dF offset);
+  void SetSubpixelPositionOffset(const gfx::Vector2dF& offset);
   const gfx::Vector2dF& subpixel_position_offset() const {
     return subpixel_position_offset_;
   }