Eliminate OmniboxMetricsProvider listening to notification

ios/chrome/browser/omnibox/omnibox_event_global_tracker.cc

Index: ios/chrome/browser/omnibox/omnibox_event_global_tracker.cc
diff --git a/ios/chrome/browser/omnibox/omnibox_event_global_tracker.cc b/ios/chrome/browser/omnibox/omnibox_event_global_tracker.cc
deleted file mode 100644
index c36153c14f157f9fa835de3498dfaef1c8f563ad..0000000000000000000000000000000000000000
--- a/ios/chrome/browser/omnibox/omnibox_event_global_tracker.cc
+++ /dev/null
@@ -1,24 +0,0 @@
-// 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_event_global_tracker.h"
-
-#include "base/memory/singleton.h"
-
-OmniboxEventGlobalTracker* OmniboxEventGlobalTracker::GetInstance() {
-  return Singleton<OmniboxEventGlobalTracker>::get();
-}
-
-scoped_ptr<base::CallbackList<void(OmniboxLog*)>::Subscription>
-OmniboxEventGlobalTracker::RegisterCallback(const OnURLOpenedCallback& cb) {
-  return on_url_opened_callback_list_.Add(cb);
-}
-
-void OmniboxEventGlobalTracker::OnURLOpened(OmniboxLog* log) {
-  on_url_opened_callback_list_.Notify(log);
-}
-
-OmniboxEventGlobalTracker::OmniboxEventGlobalTracker() {}
-
-OmniboxEventGlobalTracker::~OmniboxEventGlobalTracker() {}