CC Animation: Expose TargetProperty enum to be aliased in Blink Platform.

cc/animation/animation_target_property.h

+// Copyright (c) 2016 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 CC_ANIMATION_ANIMATION_TARGET_PROPERTY_H_
+#define CC_ANIMATION_ANIMATION_TARGET_PROPERTY_H_
+
+#include <functional>
+#include <ostream>
+
+#include "cc/base/cc_export.h"
+
+namespace cc {
+
+enum class AnimationTargetProperty : int {
+  TRANSFORM = 0,
+  OPACITY,
+  FILTER,
+  SCROLL_OFFSET,
+  BACKGROUND_COLOR,
+  // This sentinel must be last.
+  LAST_TARGET_PROPERTY = BACKGROUND_COLOR
+};
+
+const char* GetAnimationTargetPropertyName(AnimationTargetProperty property);
+
+std::ostream& CC_EXPORT operator<<(std::ostream& out,
+                                   AnimationTargetProperty property);
+
+}  // namespace cc
+
+namespace std {
+
+template <>
+inline size_t hash<cc::AnimationTargetProperty>::operator()(

[jbroman, 2016/02/16 15:56:43]

http://chromium-cpp.appspot.com/ and the Google C++ style guide say we shouldn't
specialize std::hash.

+    cc::AnimationTargetProperty property) const {
+  return static_cast<size_t>(property);
+}
+}

[loyso (OOO), 2016/02/15 06:40:37]

We need some common traits (a macro) to work with strongly-typed enums and
implement all these helpers.

+
+#endif  // CC_ANIMATION_ANIMATION_TARGET_PROPERTY_H_