Upstream iOS UI utilities.

ios/chrome/browser/ui/reversed_animation.h

Index: ios/chrome/browser/ui/reversed_animation.h
diff --git a/ios/chrome/browser/ui/reversed_animation.h b/ios/chrome/browser/ui/reversed_animation.h
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+++ b/ios/chrome/browser/ui/reversed_animation.h
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+// Copyright 2014 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 IOS_CHROME_BROWSER_UI_REVERSED_ANIMATION_H_
+#define IOS_CHROME_BROWSER_UI_REVERSED_ANIMATION_H_
+
+#import <UIKit/UIKit.h>
+
+// Returns an animation that reverses |animation| when added to |layer|.
+CAAnimation* CAAnimationMakeReverse(CAAnimation* animation, CALayer* layer);
+
+// Removes the animation for |key| from each CALayer in |layers|, creates
+// reversed versions using |CAAnimationMakeReverse|, then adds the reversed
+// animation back to the layers under the same key.
+void ReverseAnimationsForKeyForLayers(NSString* key, NSArray* layers);
+
+#endif  // IOS_CHROME_BROWSER_UI_REVERSED_ANIMATION_H_