Implement frames() timing function

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

Index: third_party/WebKit/Source/platform/animation/TimingFunction.h
diff --git a/third_party/WebKit/Source/platform/animation/TimingFunction.h b/third_party/WebKit/Source/platform/animation/TimingFunction.h
index 5bad355eaeef240088660312c8289494046811a8..64302dcb9f2fde594ca7c532897ee7097ee51f77 100644
--- a/third_party/WebKit/Source/platform/animation/TimingFunction.h
+++ b/third_party/WebKit/Source/platform/animation/TimingFunction.h
@@ -222,6 +222,30 @@ class PLATFORM_EXPORT StepsTimingFunction final : public TimingFunction {
   std::unique_ptr<cc::StepsTimingFunction> m_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* minValue, double* maxValue) const override;
+  std::unique_ptr<cc::TimingFunction> cloneToCC() const override;
+
+  int numberOfFrames() const { return m_frames->frames(); }
+
+ private:
+  FramesTimingFunction(int frames)
+      : TimingFunction(Type::FRAMES),
+        m_frames(cc::FramesTimingFunction::Create(frames)) {}
+
+  std::unique_ptr<cc::FramesTimingFunction> m_frames;
+};
+
 PLATFORM_EXPORT PassRefPtr<TimingFunction> createCompositorTimingFunctionFromCC(
     const cc::TimingFunction*);
 
@@ -231,6 +255,8 @@ 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&);
@@ -243,6 +269,7 @@ PLATFORM_EXPORT bool operator!=(const TimingFunction&, const TimingFunction&);
 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