Implement AnimationEffectTimingReadOnly interface

third_party/WebKit/Source/core/animation/AnimationEffectReadOnly.h

Index: third_party/WebKit/Source/core/animation/AnimationEffectReadOnly.h
diff --git a/third_party/WebKit/Source/core/animation/AnimationEffectReadOnly.h b/third_party/WebKit/Source/core/animation/AnimationEffectReadOnly.h
index fa41e7f5d0c98de08fa618a686df19684b9e172d..78f72e037b7488c5ba60b3f5ca36699199d6edf0 100644
--- a/third_party/WebKit/Source/core/animation/AnimationEffectReadOnly.h
+++ b/third_party/WebKit/Source/core/animation/AnimationEffectReadOnly.h
@@ -40,7 +40,7 @@ namespace blink {
 
 class Animation;
 class AnimationEffectReadOnly;
-class AnimationEffectTiming;
+class AnimationEffectTimingReadOnly;
 class ComputedTimingProperties;
 
 enum TimingUpdateReason {
@@ -101,7 +101,7 @@ public:
     const Animation* animation() const { return m_animation; }
     Animation* animation() { return m_animation; }
     const Timing& specifiedTiming() const { return m_timing; }
-    AnimationEffectTiming* timing();
+    virtual AnimationEffectTimingReadOnly* timing();
     void updateSpecifiedTiming(const Timing&);
 
     void getComputedTiming(ComputedTimingProperties&);