Refactor extension app icon.

chrome/browser/extensions/extension_app_icon_service_factory.h

+// Copyright 2017 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.
+
+#ifndef CHROME_BROWSER_EXTENSIONS_EXTENSION_APP_ICON_SERVICE_FACTORY_H_
+#define CHROME_BROWSER_EXTENSIONS_EXTENSION_APP_ICON_SERVICE_FACTORY_H_
+
+#include "base/macros.h"
+#include "base/memory/singleton.h"
+#include "components/keyed_service/content/browser_context_keyed_service_factory.h"
+
+namespace extensions {
+
+class ExtensionAppIconService;
+
+// Factory to create ExtensionAppIconService. Use helper
+// ExtensionAppIconService::Get(context) to access the service.
+class ExtensionAppIconServiceFactory
+    : public BrowserContextKeyedServiceFactory {
+ public:
+  static ExtensionAppIconService* GetForBrowserContext(
+      content::BrowserContext* context);
+
+  static ExtensionAppIconServiceFactory* GetInstance();
+
+ private:
+  friend struct base::DefaultSingletonTraits<ExtensionAppIconServiceFactory>;
+
+  ExtensionAppIconServiceFactory();
+  ~ExtensionAppIconServiceFactory() override;
+
+  KeyedService* BuildServiceInstanceFor(
+      content::BrowserContext* context) const override;
+  content::BrowserContext* GetBrowserContextToUse(
+      content::BrowserContext* context) const override;
+
+  DISALLOW_COPY_AND_ASSIGN(ExtensionAppIconServiceFactory);
+};
+
+}  // namespace extensions
+
+#endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_APP_ICON_SERVICE_FACTORY_H_