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

ios/chrome/browser/ui/settings/utils/fake_observable_boolean.mm

+// Copyright 2016 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/ui/settings/utils/fake_observable_boolean.h"
+
+@implementation FakeObservableBoolean
+
+@synthesize value = _value;
+@synthesize observer = _observer;
+
+- (void)setValue:(BOOL)value {
+  bool changed = value != _value;
+  _value = value;
+  if (changed)
+    [self.observer booleanDidChange:self];
+}
+
+@end
+
+@implementation TestBooleanObserver
+
+@synthesize updateCount = _updateCount;
+
+- (void)booleanDidChange:(id<ObservableBoolean>)observableBoolean {
+  self.updateCount++;
+}
+
+@end