Upstream Chrome on iOS source code [8/11].

ios/chrome/browser/ui/side_swipe/side_swipe_navigation_view.h

+// Copyright 2015 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_SIDE_SWIPE_SIDE_SWIPE_NAVIGATION_VIEW_H_
+#define IOS_CHROME_BROWSER_UI_SIDE_SWIPE_SIDE_SWIPE_NAVIGATION_VIEW_H_
+
+#import <UIKit/UIKit.h>
+
+@class SideSwipeGestureRecognizer;
+
+// Accessory view showing forward or back arrow while the main target view
+// is dragged from side to side.
+@interface SideSwipeNavigationView : UIView
+
+@property(nonatomic, assign) UIView* targetView;
+
+// Initialize with direction.
+- (instancetype)initWithFrame:(CGRect)frame
+                withDirection:(UISwipeGestureRecognizerDirection)direction
+                  canNavigate:(BOOL)canNavigate
+                        image:(UIImage*)image
+                rotateForward:(BOOL)rotateForward;
+
+// Update views for latest gesture, and call completion blocks whether
+// |threshold| is met.
+- (void)handleHorizontalPan:(SideSwipeGestureRecognizer*)gesture
+     onOverThresholdCompletion:(void (^)(void))onOverThresholdCompletion
+    onUnderThresholdCompletion:(void (^)(void))onUnderThresholdCompletion;
+@end
+
+#endif  // IOS_CHROME_BROWSER_UI_SIDE_SWIPE_SIDE_SWIPE_NAVIGATION_VIEW_H_