Allow transitions on background-size with positionally matched keywords

third_party/WebKit/Source/core/animation/animatable/AnimatableUnknown.h

Index: third_party/WebKit/Source/core/animation/animatable/AnimatableUnknown.h
diff --git a/third_party/WebKit/Source/core/animation/animatable/AnimatableUnknown.h b/third_party/WebKit/Source/core/animation/animatable/AnimatableUnknown.h
index 8ff14ad2cc94096aa53672d62ef8ee100406d344..eeb4ad718154feea9e2b7cd62fc6d503c7a59629 100644
--- a/third_party/WebKit/Source/core/animation/animatable/AnimatableUnknown.h
+++ b/third_party/WebKit/Source/core/animation/animatable/AnimatableUnknown.h
@@ -59,7 +59,7 @@ protected:
         return defaultInterpolateTo(this, value, fraction);
     }
 
-    bool usesDefaultInterpolationWith(const AnimatableValue*) const override { return true; }
+    bool usesDefaultInterpolationWith(const AnimatableValue*) const override;
 
 private:
     explicit AnimatableUnknown(CSSValue* value)
@@ -81,6 +81,12 @@ inline bool AnimatableUnknown::equalTo(const AnimatableValue* value) const
     return m_value == unknown->m_value || m_value->equals(*unknown->m_value);
 }
 
+inline bool AnimatableUnknown::usesDefaultInterpolationWith(const AnimatableValue* value) const
+{
+    const AnimatableUnknown& unknown = toAnimatableUnknown(*value);
+    return !m_value->equals(*unknown.m_value);
+}
+
 } // namespace blink
 
 #endif // AnimatableUnknown_h