Implements N:M forwarding of OmniboxEditModel events on iOS.

ios/chrome/browser/omnibox/omnibox_edit_model_observer_relay.cc

+// Copyright 2015 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 "ios/chrome/browser/omnibox/omnibox_edit_model_observer_relay.h"
+
+#include "base/memory/singleton.h"
+
+OmniboxEditModelObserverRelay* OmniboxEditModelObserverRelay::GetInstance() {
+  return Singleton<OmniboxEditModelObserverRelay>::get();
+}
+
+scoped_ptr<base::CallbackList<void(OmniboxLog*)>::Subscription>
+OmniboxEditModelObserverRelay::RegisterCallback(const OnURLOpenedCallback& cb) {
+  return on_url_opened_callback_list_.Add(cb);
+}
+
+void OmniboxEditModelObserverRelay::OnURLOpened(OmniboxLog* log) {
+  on_url_opened_callback_list_.Notify(log);
+}
+
+OmniboxEditModelObserverRelay::OmniboxEditModelObserverRelay() {}
+
+OmniboxEditModelObserverRelay::~OmniboxEditModelObserverRelay() {}