Upstream Chrome on iOS source code [2/11].

ios/chrome/browser/sessions/NSCoder+Compatibility.h

+// 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_SESSIONS_NSCODER_COMPATIBILITY_H_
+#define IOS_CHROME_BROWSER_SESSIONS_NSCODER_COMPATIBILITY_H_
+
+#import <Foundation/Foundation.h>
+
+@interface NSCoder (Compatibility)
+
+// Decodes and returns a 32-bit or 64-bit integer value that was previously
+// encoded with |cr_encodeIndex:forKey:| and associated with |key|. Handles
+// with special care |NSNotFound| value to be portable between 32-bit and
+// 64-bit binaries.
+- (NSInteger)cr_decodeIndexForKey:(NSString*)key;
+
+// Encodes the 32-bit or 64-bit integer |index| and associates it with |key|.
+// Handles with special care |NSNotFound| value to be portable between 32-bit
+// and 64-bit binaries.
+- (void)cr_encodeIndex:(NSInteger)index forKey:(NSString*)key;
+
+@end
+
+#endif  // IOS_CHROME_BROWSER_SESSIONS_NSCODER_COMPATIBILITY_H_