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

cc/animation/scroll_offset_animation_curve.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/animation/scroll_offset_animation_curve.h"
 
 #include <algorithm>
 #include <cmath>
 
 #include "base/logging.h"
 #include "cc/animation/timing_function.h"
 #include "ui/gfx/animation/tween.h"
 
 const double kDurationDivisor = 60.0;
 
 namespace cc {
 
 scoped_ptr<ScrollOffsetAnimationCurve> ScrollOffsetAnimationCurve::Create(
-    gfx::Vector2dF target_value,
+    const gfx::Vector2dF& target_value,
     scoped_ptr<TimingFunction> timing_function) {
   return make_scoped_ptr(
       new ScrollOffsetAnimationCurve(target_value, timing_function.Pass()));
 }
 
 ScrollOffsetAnimationCurve::ScrollOffsetAnimationCurve(
-    gfx::Vector2dF target_value,
+    const gfx::Vector2dF& target_value,
     scoped_ptr<TimingFunction> timing_function)
     : target_value_(target_value),
       duration_(0.0),
       timing_function_(timing_function.Pass()) {}
 
 ScrollOffsetAnimationCurve::~ScrollOffsetAnimationCurve() {}
 
-void ScrollOffsetAnimationCurve::SetInitialValue(gfx::Vector2dF initial_value) {
+void ScrollOffsetAnimationCurve::SetInitialValue(
+    const gfx::Vector2dF& initial_value) {
   initial_value_ = initial_value;
 
   // The duration of a scroll animation depends on the size of the scroll.
   // The exact relationship between the size and the duration isn't specified
   // by the CSSOM View smooth scroll spec and is instead left up to user agents
   // to decide. The calculation performed here will very likely be further
   // tweaked before the smooth scroll API ships.
   float delta_x = std::abs(target_value_.x() - initial_value_.x());
   float delta_y = std::abs(target_value_.y() - initial_value_.y());
   float max_delta = std::max(delta_x, delta_y);
@@ skipping 26 matching lines @@
   scoped_ptr<TimingFunction> timing_function(
       static_cast<TimingFunction*>(timing_function_->Clone().release()));
   scoped_ptr<ScrollOffsetAnimationCurve> curve_clone =
       Create(target_value_, timing_function.Pass());
   curve_clone->initial_value_ = initial_value_;
   curve_clone->duration_ = duration_;
   return curve_clone.PassAs<AnimationCurve>();
 }
 
 }  // namespace cc