Use a bitfield to store animatable properties.

ash/rotator/screen_rotation.cc

 // Copyright (c) 2012 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.
 
 #include "ash/rotator/screen_rotation.h"
 
 #include "base/time/time.h"
 #include "ui/compositor/layer.h"
 #include "ui/gfx/interpolated_transform.h"
 #include "ui/gfx/rect.h"
@@ skipping 13 matching lines @@
   if (degrees == 180)
     return base::TimeDelta::FromMilliseconds(k180DegreeTransitionDurationMs);
   if (degrees == 0)
     return base::TimeDelta::FromMilliseconds(0);
   return base::TimeDelta::FromMilliseconds(k90DegreeTransitionDurationMs);
 }
 
 }  // namespace
 
 ScreenRotation::ScreenRotation(int degrees, ui::Layer* layer)
-    : ui::LayerAnimationElement(GetProperties(),
+    : ui::LayerAnimationElement(LayerAnimationElement::TRANSFORM,
                                 GetTransitionDuration(degrees)),
       degrees_(degrees) {
   InitTransform(layer);
 }
 
 ScreenRotation::~ScreenRotation() {
 }
 
 void ScreenRotation::InitTransform(ui::Layer* layer) {
   // No rotation required, use the identity transform.
@@ skipping 68 matching lines @@
   return true;
 }
 
 void ScreenRotation::OnGetTarget(TargetValue* target) const {
   target->transform = interpolated_transform_->Interpolate(1.0);
 }
 
 void ScreenRotation::OnAbort(ui::LayerAnimationDelegate* delegate) {
 }
 
-// static
-const ui::LayerAnimationElement::AnimatableProperties&
-ScreenRotation::GetProperties() {
-  static ui::LayerAnimationElement::AnimatableProperties properties;
-  if (properties.empty())
-    properties.insert(ui::LayerAnimationElement::TRANSFORM);
-  return properties;
-}
-
 }  // namespace ash