CC should use TimeTicks and TimeDelta to represent time

cc/input/page_scale_animation.cc

 // Copyright 2012 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/input/page_scale_animation.h"
 
 #include <math.h>
 
 #include "base/logging.h"
 #include "cc/animation/timing_function.h"
@@ skipping 148 matching lines @@
 }
 
 gfx::SizeF PageScaleAnimation::ViewportSizeAt(float interp) const {
   return gfx::ScaleSize(viewport_size_, 1.f / PageScaleFactorAt(interp));
 }
 
 bool PageScaleAnimation::IsAnimationStarted() const {
   return start_time_ >= 0;
 }
 
-void PageScaleAnimation::StartAnimation(double time) {
+void PageScaleAnimation::StartAnimation(base::TimeTicks time) {
   DCHECK_GT(0, start_time_);
-  start_time_ = time;
+  start_time_ = (time - base::TimeTicks()).InSecondsF();
 }
 
-gfx::Vector2dF PageScaleAnimation::ScrollOffsetAtTime(double time) const {
+gfx::Vector2dF PageScaleAnimation::ScrollOffsetAtTime(
+    base::TimeTicks time) const {
   DCHECK_GE(start_time_, 0);
   return ScrollOffsetAt(InterpAtTime(time));
 }
 
-float PageScaleAnimation::PageScaleFactorAtTime(double time) const {
+float PageScaleAnimation::PageScaleFactorAtTime(base::TimeTicks time) const {
   DCHECK_GE(start_time_, 0);
   return PageScaleFactorAt(InterpAtTime(time));
 }
 
-bool PageScaleAnimation::IsAnimationCompleteAtTime(double time) const {
+bool PageScaleAnimation::IsAnimationCompleteAtTime(base::TimeTicks time) const {
   DCHECK_GE(start_time_, 0);
-  return time >= end_time();
+  return (time - base::TimeTicks()).InSecondsF() >= end_time();
 }
 
-float PageScaleAnimation::InterpAtTime(double time) const {
+float PageScaleAnimation::InterpAtTime(base::TimeTicks time) const {
   DCHECK_GE(start_time_, 0);
-  DCHECK_GE(time, start_time_);
+  DCHECK_GE((time - base::TimeTicks()).InSecondsF(), start_time_);
   if (IsAnimationCompleteAtTime(time))
     return 1.f;
-
-  const double normalized_time = (time - start_time_) / duration_;
+  double monotonic_time = (time - base::TimeTicks()).InSecondsF();
+  const double normalized_time = (monotonic_time - start_time_) / duration_;
   return timing_function_->GetValue(normalized_time);
 }
 
 gfx::Vector2dF PageScaleAnimation::ScrollOffsetAt(float interp) const {
   if (interp <= 0.f)
     return start_scroll_offset_;
   if (interp >= 1.f)
     return target_scroll_offset_;
 
   return AnchorAt(interp) - ViewportRelativeAnchorAt(interp);
@@ skipping 27 matching lines @@
 
   // Linearly interpolate the magnitude in log scale.
   float diff = target_page_scale_factor_ / start_page_scale_factor_;
   float log_diff = log(diff);
   log_diff *= interp;
   diff = exp(log_diff);
   return start_page_scale_factor_ * diff;
 }
 
 }  // namespace cc