Basic ScrollTimeline implementation for Animation Worklet

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

+// Copyright 2017 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 ScrollTimeline_h
+#define ScrollTimeline_h
+
+#include "core/CoreExport.h"
+#include "core/animation/AnimationTimeline.h"
+#include "core/animation/ScrollTimelineOptions.h"
+#include "core/dom/Element.h"
+#include "platform/bindings/ScriptWrappable.h"
+#include "platform/wtf/text/WTFString.h"
+
+namespace blink {
+
+class CORE_EXPORT ScrollTimeline final : public AnimationTimeline {
+  DEFINE_WRAPPERTYPEINFO();
+
+ public:
+  enum ScrollDirection {
+    Auto,
+    Block,
+    Inline,
+  };
+
+  static ScrollTimeline* Create(Document&,
+                                ScrollTimelineOptions,
+                                ExceptionState&);
+
+  // AnimationTimeline overrides.
+  // TODO(smcgruer): We shouldn't have to override this many methods. Instead,
+  // DocumentTimeline should own the |CurrentTimeInternal| methods so that we
+  // only have to override |currentTime|.
+  double currentTime(bool& is_null) override;
+  double currentTime() override;
+  double CurrentTimeInternal(bool& is_null) override;
+  double CurrentTimeInternal() override;
+
+  // IDL API implementation.
+  Element* scrollSource();
+  String orientation();
+  void timeRange(DoubleOrScrollTimelineAutoKeyword&);
+
+  DECLARE_VIRTUAL_TRACE();
+
+ private:
+  ScrollTimeline(const Document&, Element*, ScrollDirection, double);
+
+  Member<Element> scroll_source_;
+  ScrollDirection orientation_;
+  double time_range_;
+};
+
+}  // namespace blink
+
+#endif