Pass gfx structs by const ref(gfx::Vector2D/F)

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 "cc/base/time_util.h"
 #include "ui/gfx/animation/tween.h"
 
 const double kDurationDivisor = 60.0;
 
 namespace cc {
 
 namespace {
 
-static float MaximumDimension(gfx::Vector2dF delta) {
+static float MaximumDimension(const gfx::Vector2dF& delta) {
   return std::max(std::abs(delta.x()), std::abs(delta.y()));
 }
 
-static base::TimeDelta DurationFromDelta(gfx::Vector2dF delta) {
+static base::TimeDelta DurationFromDelta(const gfx::Vector2dF& delta) {
   // 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.
   return base::TimeDelta::FromMicroseconds(
       (std::sqrt(MaximumDimension(delta)) / kDurationDivisor) *
       base::Time::kMicrosecondsPerSecond);
 }
 
@@ skipping 91 matching lines @@
       (MaximumDimension(old_delta) / MaximumDimension(new_delta));
 
   initial_value_ = current_position;
   target_value_ = new_target;
   total_animation_duration_ = base::TimeDelta::FromSecondsD(t + new_duration);
   last_retarget_ = base::TimeDelta::FromSecondsD(t);
   timing_function_ = EaseOutWithInitialVelocity(new_velocity);
 }
 
 }  // namespace cc