Introduce HistoryClient interface

chrome/browser/history/history_client_factory.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/history_client_factory.h"
+
+#include "chrome/browser/profiles/incognito_helpers.h"
+#include "chrome/browser/profiles/profile.h"
+#include "components/history/core/browser/history_client.h"
+#include "components/keyed_service/content/browser_context_dependency_manager.h"
+
+using history::HistoryClient;
+
+// static
+HistoryClient* HistoryClientFactory::GetForProfile(Profile* profile) {
+  return static_cast<history::HistoryClient*>(
+      GetInstance()->GetServiceForBrowserContext(profile, true));
+}
+
+// static
+HistoryClient* HistoryClientFactory::GetForProfileIfExists(Profile* profile) {
+  return static_cast<history::HistoryClient*>(
+      GetInstance()->GetServiceForBrowserContext(profile, false));
+}
+
+// static
+HistoryClientFactory* HistoryClientFactory::GetInstance() {
+  return Singleton<HistoryClientFactory>::get();
+}
+
+HistoryClientFactory::HistoryClientFactory()
+    : BrowserContextKeyedServiceFactory(
+          "HistoryClient",
+          BrowserContextDependencyManager::GetInstance()) {
+}
+
+HistoryClientFactory::~HistoryClientFactory() {
+}
+
+KeyedService* HistoryClientFactory::BuildServiceInstanceFor(
+    content::BrowserContext* context) const {
+  return new HistoryClient();
+}
+
+content::BrowserContext* HistoryClientFactory::GetBrowserContextToUse(
+    content::BrowserContext* context) const {
+  return chrome::GetBrowserContextRedirectedInIncognito(context);
+}
+
+bool HistoryClientFactory::ServiceIsNULLWhileTesting() const {
+  return true;
+}