Add foundation for removing AnimatableValues from StyleInterpolation

Source/core/animation/AnimationValue.h

+// Copyright 2015 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 AnimationValue_h
+#define AnimationValue_h
+
+#include "core/animation/InterpolableValue.h"
+#include "core/animation/NonInterpolableValue.h"
+#include "platform/heap/Handle.h"
+
+namespace blink {
+
+class InterpolableValue;
+
+struct AnimationValue {
+    const AnimationType* type;
+    OwnPtrWillBeMember<InterpolableValue> interpolableValue;
+    RefPtrWillBeMember<NonInterpolableValue> nonInterpolableValue;
+
+    operator bool() const { return bool(type); }
+
+    AnimationValue()
+        : type(nullptr)
+        , interpolableValue(nullptr)
+        , nonInterpolableValue(nullptr)
+    { }
+
+    AnimationValue(const AnimationType* type, PassOwnPtrWillBeRawPtr<InterpolableValue> interpolableValue, RefPtrWillBeRawPtr<NonInterpolableValue> nonInterpolableValue)
+        : type(type)
+        , interpolableValue(interpolableValue)
+        , nonInterpolableValue(nonInterpolableValue)
+    { }
+
+    AnimationValue(const AnimationValue&) = delete;
+    AnimationValue(AnimationValue&& other)
+        : type(other.type)
+        , interpolableValue(other.interpolableValue.release())
+        , nonInterpolableValue(other.nonInterpolableValue.release())
+    {
+        other.type = nullptr;
+    }
+
+    void copy(const AnimationValue& other)
+    {
+        type = other.type;
+        interpolableValue = other.interpolableValue ? other.interpolableValue->clone() : nullptr;

[shans, 2015/05/28 05:48:13]

Are AnimationValues mutable? I can't think of a strong reason why the
interpolableValue would be mutated (as opposed to maybe just replaced depending
on implementation details).

[alancutter (OOO until 2018), 2015/06/01 07:35:28]

They are mutable as a consequence of InterpolableValues being mutable.
InterpolableValue::interpolate() mutates its InterpolableValue out parameter.

+        nonInterpolableValue = other.nonInterpolableValue;
+    }
+
+    void clear()
+    {
+        type = nullptr;
+        interpolableValue = nullptr;
+        nonInterpolableValue = nullptr;
+    }
+
+    void consume(AnimationValue& other)

[shans, 2015/05/28 05:48:13]

what is consume?

[alancutter (OOO until 2018), 2015/06/01 07:35:28]

Renamed to swap() to match Vector::swap() and added comment.
Once Oilpan lands this can be removed as InterpolableValues will cease to be
OwnPtr'd.

+    {
+        type = other.type;
+        other.type = nullptr;
+        interpolableValue = other.interpolableValue.release();
+        nonInterpolableValue = other.nonInterpolableValue.release();
+    }
+
+    DEFINE_INLINE_TRACE()
+    {
+        visitor->trace(interpolableValue);
+        visitor->trace(nonInterpolableValue);
+    }
+private:
+    DISALLOW_ALLOCATION();
+};
+
+} // namespace blink
+
+#endif // AnimationValue_h