Implement frames() timing function

third_party/WebKit/Source/platform/animation/TimingFunction.h

 /*
  * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
  *           (C) 2000 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2003, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Graham Dennis (graham.dennis@gmail.com)
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
@@ skipping 204 matching lines @@
   StepPosition GetStepPosition() const { return steps_->step_position(); }
 
  private:
   StepsTimingFunction(int steps, StepPosition step_position)
       : TimingFunction(Type::STEPS),
         steps_(cc::StepsTimingFunction::Create(steps, step_position)) {}
 
   std::unique_ptr<cc::StepsTimingFunction> steps_;
 };
 
+class PLATFORM_EXPORT FramesTimingFunction final : public TimingFunction {
+ public:
+  static PassRefPtr<FramesTimingFunction> Create(int frames) {
+    return AdoptRef(new FramesTimingFunction(frames));
+  }
+
+  ~FramesTimingFunction() override {}
+
+  // TimingFunction implementation.
+  String ToString() const override;
+  double Evaluate(double fraction, double) const override;
+  void Range(double* min_value, double* max_value) const override;
+  std::unique_ptr<cc::TimingFunction> CloneToCC() const override;
+
+  int NumberOfFrames() const { return frames_->frames(); }
+
+ private:
+  FramesTimingFunction(int frames)
+      : TimingFunction(Type::FRAMES),
+        frames_(cc::FramesTimingFunction::Create(frames)) {}
+
+  std::unique_ptr<cc::FramesTimingFunction> frames_;
+};
+
 PLATFORM_EXPORT PassRefPtr<TimingFunction> CreateCompositorTimingFunctionFromCC(
     const cc::TimingFunction*);
 
 PLATFORM_EXPORT bool operator==(const LinearTimingFunction&,
                                 const TimingFunction&);
 PLATFORM_EXPORT bool operator==(const CubicBezierTimingFunction&,
                                 const TimingFunction&);
 PLATFORM_EXPORT bool operator==(const StepsTimingFunction&,
                                 const TimingFunction&);
+PLATFORM_EXPORT bool operator==(const FramesTimingFunction&,
+                                const TimingFunction&);
 
 PLATFORM_EXPORT bool operator==(const TimingFunction&, const TimingFunction&);
 PLATFORM_EXPORT bool operator!=(const TimingFunction&, const TimingFunction&);
 
 #define DEFINE_TIMING_FUNCTION_TYPE_CASTS(typeName, enumName)           \
   DEFINE_TYPE_CASTS(typeName##TimingFunction, TimingFunction, value,    \
                     value->GetType() == TimingFunction::Type::enumName, \
                     value.GetType() == TimingFunction::Type::enumName)
 
 DEFINE_TIMING_FUNCTION_TYPE_CASTS(Linear, LINEAR);
 DEFINE_TIMING_FUNCTION_TYPE_CASTS(CubicBezier, CUBIC_BEZIER);
 DEFINE_TIMING_FUNCTION_TYPE_CASTS(Steps, STEPS);
+DEFINE_TIMING_FUNCTION_TYPE_CASTS(Frames, FRAMES);
 
 }  // namespace blink
 
 #endif  // TimingFunction_h