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

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

+// 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.
+
+#import "ios/chrome/browser/sessions/NSCoder+Compatibility.h"
+
+#include "base/logging.h"
+
+namespace {
+// Note: |NSNotFound| is equal to |NSIntegerMax| in 32-bit and 64-bit that
+// in turn is initialized to |LONG_MAX|. On a 32-bit build, |INT_MAX| and
+// |LONG_MAX| have the same value, however, in a 64-bit build, |LONG_MAX|
+// is much larger, so we define |NSNotFound32| to |INT_MAX| that has the
+// same value in both 32-bit and 64-bit builds.
+enum { NSNotFound32 = INT_MAX };
+}  // namespace
+
+@implementation NSCoder (Compatibility)
+
+- (NSInteger)cr_decodeIndexForKey:(NSString*)key {
+  int32_t index32 = [self decodeInt32ForKey:key];
+  DCHECK(0 <= index32 && index32 <= NSNotFound32);
+  return index32 == NSNotFound32 ? NSNotFound : static_cast<NSInteger>(index32);
+}
+
+- (void)cr_encodeIndex:(NSInteger)index forKey:(NSString*)key {
+  DCHECK((0 <= index && index < NSNotFound32) || index == NSNotFound);
+  int32_t index32 = index == NSNotFound ? static_cast<int32_t>(NSNotFound32)
+                                        : static_cast<int32_t>(index);
+  [self encodeInt32:index32 forKey:key];
+}
+
+@end