CC::Animations should use TimeTicks & TimeDelta to represent time

cc/input/page_scale_animation.h

 // Copyright 2011 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.
 
 #ifndef CC_INPUT_PAGE_SCALE_ANIMATION_H_
 #define CC_INPUT_PAGE_SCALE_ANIMATION_H_
 
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/time/time.h"
 #include "ui/gfx/size.h"
 #include "ui/gfx/vector2d_f.h"
 
 namespace cc {
+
+using base::TimeTicks;
+using base::TimeDelta;
+
 class TimingFunction;
 
 // A small helper class that does the math for zoom animations, primarily for
 // double-tap zoom. Initialize it with starting and ending scroll/page scale
 // positions and an animation length time, then call ...AtTime() at every frame
 // to obtain the current interpolated position. The supplied timing function
 // is used to ease the animation.
 //
 // All sizes and vectors in this class's public methods are in the root scroll
 // layer's coordinate space.
@@ skipping 21 matching lines @@
   // at the same position on the physical display throughout the animation,
   // unless the edges of the root layer are hit. The anchor is specified
   // as an offset from the content layer.
   void ZoomWithAnchor(const gfx::Vector2dF& anchor,
                       float target_page_scale_factor,
                       double duration);
 
   // These should be called before the first frame of animation to initialize
   // the start time. StartAnimation should only be called once after creation.
   bool IsAnimationStarted() const;
-  void StartAnimation(double time);
+  void StartAnimation(base::TimeTicks time);
 
   // Call these functions while the animation is in progress to output the
   // current state.
-  gfx::Vector2dF ScrollOffsetAtTime(double time) const;
-  float PageScaleFactorAtTime(double time) const;
-  bool IsAnimationCompleteAtTime(double time) const;
+  gfx::Vector2dF ScrollOffsetAtTime(base::TimeTicks time) const;
+  float PageScaleFactorAtTime(base::TimeTicks time) const;
+  bool IsAnimationCompleteAtTime(base::TimeTicks time) const;
 
   // The following methods return state which is invariant throughout the
   // course of the animation.
-  double start_time() const { return start_time_; }
-  double duration() const { return duration_; }
-  double end_time() const { return start_time_ + duration_; }
+  TimeTicks start_time() const { return start_time_; }
+  TimeDelta duration() const { return duration_; }
+  TimeTicks end_time() const { return start_time_ + duration_; }
   gfx::Vector2dF target_scroll_offset() const { return target_scroll_offset_; }
   float target_page_scale_factor() const { return target_page_scale_factor_; }
 
  protected:
   PageScaleAnimation(const gfx::Vector2dF& start_scroll_offset,
                      float start_page_scale_factor,
                      const gfx::SizeF& viewport_size,
                      const gfx::SizeF& root_layer_size,
                      scoped_ptr<TimingFunction> timing_function);
 
  private:
   void ClampTargetScrollOffset();
   void InferTargetScrollOffsetFromStartAnchor();
   void InferTargetAnchorFromScrollOffsets();
 
   gfx::SizeF StartViewportSize() const;
   gfx::SizeF TargetViewportSize() const;
-  float InterpAtTime(double time) const;
+  float InterpAtTime(base::TimeTicks time) const;
   gfx::SizeF ViewportSizeAt(float interp) const;
   gfx::Vector2dF ScrollOffsetAt(float interp) const;
   gfx::Vector2dF AnchorAt(float interp) const;
   gfx::Vector2dF ViewportRelativeAnchorAt(float interp) const;
   float PageScaleFactorAt(float interp) const;
 
   float start_page_scale_factor_;
   float target_page_scale_factor_;
   gfx::Vector2dF start_scroll_offset_;
   gfx::Vector2dF target_scroll_offset_;
 
   gfx::Vector2dF start_anchor_;
   gfx::Vector2dF target_anchor_;
 
   gfx::SizeF viewport_size_;
   gfx::SizeF root_layer_size_;
 
-  double start_time_;
-  double duration_;
+  TimeTicks start_time_;
+  TimeDelta duration_;
 
   scoped_ptr<TimingFunction> timing_function_;
 
   DISALLOW_COPY_AND_ASSIGN(PageScaleAnimation);
 };
 
 }  // namespace cc
 
 #endif  // CC_INPUT_PAGE_SCALE_ANIMATION_H_