[#5] Pass gfx structs by const ref (gfx::Vector2dF)

cc/input/page_scale_animation.cc

Index: cc/input/page_scale_animation.cc
diff --git a/cc/input/page_scale_animation.cc b/cc/input/page_scale_animation.cc
index 88b64d59d10b037c99fde0e87a8b3f341b98ed44..7df0244ec0907a1466bc2ab9625c147fe075d754 100644
--- a/cc/input/page_scale_animation.cc
+++ b/cc/input/page_scale_animation.cc
@@ -16,22 +16,22 @@ namespace {
 
 // This takes a viewport-relative vector and returns a vector whose values are
 // between 0 and 1, representing the percentage position within the viewport.
-gfx::Vector2dF NormalizeFromViewport(gfx::Vector2dF denormalized,
+gfx::Vector2dF NormalizeFromViewport(const gfx::Vector2dF& denormalized,
                                      const gfx::SizeF& viewport_size) {
   return gfx::ScaleVector2d(denormalized,
                             1.f / viewport_size.width(),
                             1.f / viewport_size.height());
 }
 
-gfx::Vector2dF DenormalizeToViewport(gfx::Vector2dF normalized,
+gfx::Vector2dF DenormalizeToViewport(const gfx::Vector2dF& normalized,
                                      const gfx::SizeF& viewport_size) {
   return gfx::ScaleVector2d(normalized,
                             viewport_size.width(),
                             viewport_size.height());
 }
 
-gfx::Vector2dF InterpolateBetween(gfx::Vector2dF start,
-                                  gfx::Vector2dF end,
+gfx::Vector2dF InterpolateBetween(const gfx::Vector2dF& start,
+                                  const gfx::Vector2dF& end,
                                   float interp) {
   return start + gfx::ScaleVector2d(end - start, interp);
 }
@@ -41,7 +41,7 @@ gfx::Vector2dF InterpolateBetween(gfx::Vector2dF start,
 namespace cc {
 
 scoped_ptr<PageScaleAnimation> PageScaleAnimation::Create(
-    gfx::Vector2dF start_scroll_offset,
+    const gfx::Vector2dF& start_scroll_offset,
     float start_page_scale_factor,
     const gfx::SizeF& viewport_size,
     const gfx::SizeF& root_layer_size,
@@ -54,7 +54,7 @@ scoped_ptr<PageScaleAnimation> PageScaleAnimation::Create(
 }
 
 PageScaleAnimation::PageScaleAnimation(
-    gfx::Vector2dF start_scroll_offset,
+    const gfx::Vector2dF& start_scroll_offset,
     float start_page_scale_factor,
     const gfx::SizeF& viewport_size,
     const gfx::SizeF& root_layer_size,
@@ -72,7 +72,7 @@ PageScaleAnimation::PageScaleAnimation(
 
 PageScaleAnimation::~PageScaleAnimation() {}
 
-void PageScaleAnimation::ZoomTo(gfx::Vector2dF target_scroll_offset,
+void PageScaleAnimation::ZoomTo(const gfx::Vector2dF& target_scroll_offset,
                                 float target_page_scale_factor,
                                 double duration) {
   target_page_scale_factor_ = target_page_scale_factor;
@@ -92,7 +92,7 @@ void PageScaleAnimation::ZoomTo(gfx::Vector2dF target_scroll_offset,
   start_anchor_ = target_anchor_;
 }
 
-void PageScaleAnimation::ZoomWithAnchor(gfx::Vector2dF anchor,
+void PageScaleAnimation::ZoomWithAnchor(const gfx::Vector2dF& anchor,
                                         float target_page_scale_factor,
                                         double duration) {
   start_anchor_ = anchor;