Replace changes_channel with an observer list.

chrome/browser/sync/util/channel_unittest.cc

+// Copyright (c) 2010 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.
+
+#include "chrome/browser/sync/util/channel.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+struct TestEvent {
+  explicit TestEvent(int foo) : data(foo) {}
+  int data;
+};
+
+class TestObserver : public browser_sync::ChannelEventHandler<TestEvent> {
+ public:
+  virtual void HandleChannelEvent(const TestEvent& event) {
+    delete hookup;
+    hookup = 0;
+  }
+
+  browser_sync::ChannelHookup<TestEvent>* hookup;
+};
+
+TEST(ChannelTest, RemoveOnNotify) {
+  browser_sync::Channel<TestEvent> channel;
+  TestObserver observer;
+
+  observer.hookup = channel.AddObserver(&observer);
+
+  ASSERT_TRUE(0 != observer.hookup);
+  channel.Notify(TestEvent(1));
+  ASSERT_EQ(0, observer.hookup);
+}