Refactor extension app icon.

chrome/browser/extensions/extension_app_icon_service.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_H_
+#define CHROME_BROWSER_EXTENSIONS_EXTENSION_APP_ICON_SERVICE_H_
+
+#include <map>
+#include <memory>
+
+#include "base/macros.h"
+#include "base/memory/weak_ptr.h"
+#include "components/keyed_service/core/keyed_service.h"
+#include "extensions/browser/extension_registry_observer.h"
+
+namespace content {
+class BrowserContext;
+}
+
+namespace extensions {
+
+class ExtensionAppIcon;
+class ExtensionAppIconDelegate;
+
+// Factory for ExtensionAppIcon. Each created icon is tracked by this service.
+// Once some condition that affects how extension app icon should look is
+// changed then corresponded app icons are automatically updated. This service
+// is bound to content::BrowserContext.
+// Usage: ExtensionAppIconService::Get(context)->CreateIcon().
+class ExtensionAppIconService : public KeyedService,
+                                public ExtensionRegistryObserver {
+ public:
+  static ExtensionAppIconService* Create(content::BrowserContext* context);
+
+  // Convenience function to get the ExtensionAppIconService for a
+  // BrowserContext.
+  static ExtensionAppIconService* Get(content::BrowserContext* context);
+
+  ~ExtensionAppIconService() override;
+
+  // Creates extension app icon for requested app and size. Icon updates are
+  // dispatched via |delegate|.
+  std::unique_ptr<ExtensionAppIcon> CreateIcon(
+      ExtensionAppIconDelegate* delegate,
+      const std::string& app_id,
+      int resource_size_in_dip);
+
+  // KeyedService:
+  void Shutdown() override;
+
+ private:
+  friend class ExtensionAppIcon;
+
+  class Updater;
+  using IconMap = std::multimap<std::string, ExtensionAppIcon*>;
+
+  // See the Create methods.
+  explicit ExtensionAppIconService(content::BrowserContext* context);
+
+  // Called from ExtensionAppIcon DTOR.
+  void OnIconDestroyed(ExtensionAppIcon* icon);

[xiyuan, 2017/04/20 16:36:31]

Can we base::Bind this as a OnIconDestroyedClosure and pass it to
ExtensionAppIcon? This way, we could get rid of the friend class and
ExtensionAppIcon does not need to know ExtensionAppIconService.

[khmel, 2017/04/20 17:46:18]

That is nice, thanks

+
+  // Called from Updater when corresponded app icons need to be updated.
+  void OnAppUpdated(const std::string& app_id);
+
+  // ExtensionRegistryObserver:
+  void OnExtensionLoaded(content::BrowserContext* browser_context,
+                         const Extension* extension) override;
+
+  void OnExtensionUnloaded(content::BrowserContext* browser_context,
+                           const Extension* extension,
+                           UnloadedExtensionInfo::Reason reason) override;
+
+  // Unowned pointer.
+  content::BrowserContext* context_;
+
+#if defined(OS_CHROMEOS)
+  std::unique_ptr<Updater> app_updater_;
+#endif
+
+  IconMap icon_map_;
+
+  base::WeakPtrFactory<ExtensionAppIconService> weak_ptr_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(ExtensionAppIconService);
+};
+
+}  // namespace extensions
+
+#endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_APP_ICON_SERVICE_H_