Rewrite implementation of ClipboardRecentContent in Objective C.

components/open_from_clipboard/clipboard_recent_content_impl_ios.h

+// Copyright 2017 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 COMPONENTS_OPEN_FROM_CLIPBOARD_CLIPBOARD_RECENT_CONTENT_IMPL_IOS_H_
+#define COMPONENTS_OPEN_FROM_CLIPBOARD_CLIPBOARD_RECENT_CONTENT_IMPL_IOS_H_
+
+#import <Foundation/Foundation.h>
+
+// A protocol implemented by delegates to handle clipboard changes.
+@protocol ClipboardRecentContentDelegate<NSObject>
+
+- (void)onClipboardChanged;
+
+@end
+
+// Helper class returning a URL if the content of the clipboard can be turned
+// into a URL, and if it estimates that the content of the clipboard is not too
+// old.
+@interface ClipboardRecentContentImplIOS : NSObject
+
+// |delegate| is used for metrics logging and can be nil. |authorizedSchemes|
+// should contain all schemes considered valid. |groupUserDefaults| is the
+// NSUserDefaults used to store information on pasteboard entry expiration. This
+// information will be shared with other applications in the application group.
+- (instancetype)initWithAuthorizedSchemes:(NSSet<NSString*>*)authorizedSchemes
+                             userDefaults:(NSUserDefaults*)groupUserDefaults
+                                 delegate:(id<ClipboardRecentContentDelegate>)
+                                              delegate
+    NS_DESIGNATED_INITIALIZER;
+
+- (instancetype)init NS_UNAVAILABLE;
+
+// Returns the copied URL if the clipboard contains a recent URL that has not
+// been supressed. Otherwise, returns nil.
+- (NSURL*)recentURLFromClipboard;
+
+// Returns how old the content of the clipboard is.
+- (NSTimeInterval)clipboardContentAge;
+
+// Prevents GetRecentURLFromClipboard from returning anything until the
+// clipboard's content changes.
+- (void)suppressClipboardContent;
+
+// Methods below are exposed for testing purposes.
+
+// Estimation of the date when the pasteboard changed.
+@property(nonatomic, strong) NSDate* lastPasteboardChangeDate;
+
+// Saves information to the user defaults about the latest pasteboard entry.
+- (void)saveToUserDefaults;
+
+@end
+
+#endif  // COMPONENTS_OPEN_FROM_CLIPBOARD_CLIPBOARD_RECENT_CONTENT_IMPL_IOS_H_