Introduce HistoryClient interface

chrome/browser/history/chrome_history_client.cc

+// 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.
+
+#include "chrome/browser/history/chrome_history_client.h"
+
+#include "chrome/browser/history/history_service.h"
+
+namespace history {
+
+ChromeHistoryClient::ChromeHistoryClient(Profile* profile) {
+  history_service_.reset(new HistoryService(this, profile));
+}
+
+void ChromeHistoryClient::Shutdown() {
+  history_service_->Shutdown();
+}
+
+}  // namespace history