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_
+
+namespace cc {
+
+struct AnimationTargetProperty {

[loyso (OOO), 2016/02/16 06:17:37]

This can be a namespace AnimationTargetProperty

+  enum Enum {

[loyso (OOO), 2016/02/16 06:17:37]

Alternatively, we could go with global old-style enum
ANIMATION_TARGET_PROPERTY_TRANSFORM etc in cc namespace (which is weird and
unbound)

[loyso (OOO), 2016/02/17 01:27:29]

But old-style enum would not work for 'using' in blink. I.e. you can't write:
using CompositorAnimationTargetProperty = cc::AnimationTargetProperty if
AnimationTargetProperty is a enum. That's why we need a class around it.

[Ian Vollick, 2016/02/17 13:43:27]

Right, I like this approach for pulling the enum into blink. It mirrors what
Dana suggested I do here: https://codereview.chromium.org/1599673002/

+    TRANSFORM = 0,
+    OPACITY,
+    FILTER,
+    SCROLL_OFFSET,
+    BACKGROUND_COLOR,
+    // This sentinel must be last.
+    LAST_TARGET_PROPERTY = BACKGROUND_COLOR
+  };
+};
+
+const char* GetAnimationTargetPropertyName(

[loyso (OOO), 2016/02/16 06:17:36]

This can be a member function.

+    AnimationTargetProperty::Enum property);
+
+}  // namespace cc
+
+#endif  // CC_ANIMATION_ANIMATION_TARGET_PROPERTY_H_