Refactor extension app icon.

chrome/browser/extensions/extension_app_icon.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_H_
+#define CHROME_BROWSER_EXTENSIONS_EXTENSION_APP_ICON_H_
+
+#include <memory>
+#include <string>
+
+#include "base/callback.h"
+#include "base/macros.h"
+#include "extensions/browser/extension_icon_image.h"
+#include "ui/gfx/image/image_skia.h"
+
+namespace content {
+class BrowserContext;
+}
+
+namespace extensions {
+
+class Extension;
+class ExtensionAppIconDelegate;
+class IconImage;
+
+// This represents how an extension icon should finally look. As a base,
+// extension icon is used and effects that depend on extension type, state and
+// some external conditions are applied. Resulting image is sent via
+// ExtensionAppIconDelegate. Several updates are expected in case extension
+// state or some external conditions are changed.
+class ExtensionAppIcon : public extensions::IconImage::Observer {
+ public:
+  using Closure = base::Callback<void(ExtensionAppIcon*)>;

[xiyuan, 2017/04/20 17:52:46]

nit: Closure -> CloseCallback (or DestroyCallback).

Technically, this is not a closure since we need to run it with an arg. And
Closure is easy to be confused with base::Closure. 

[khmel, 2017/04/20 18:01:11]

Done.

+
+  ExtensionAppIcon(ExtensionAppIconDelegate* delegate,
+                   content::BrowserContext* context,
+                   Closure close_callback,
+                   const std::string& app_id,
+                   int resource_size_in_dip);
+  ~ExtensionAppIcon() override;
+
+  void Reload();
+
+  // Returns true if icon is loaded and attached to valid extension.
+  bool IsValid() const;
+
+  void UpdateIcon();
+
+  void EnsureRepsForSupportedScales();
+
+  const gfx::ImageSkia& image_skia() const { return image_skia_; }
+  const std::string& app_id() const { return app_id_; }
+  content::BrowserContext* context() { return context_; }
+
+ private:
+  const extensions::Extension* GetExtension();
+
+  // extensions::IconImage::Observer:
+  void OnExtensionIconImageChanged(extensions::IconImage* image) override;
+
+  // Unowned pointers.
+  ExtensionAppIconDelegate* const delegate_;
+  content::BrowserContext* const context_;
+
+  Closure close_callback_;
+
+  const std::string app_id_;
+
+  const int resource_size_in_dip_;
+
+  // Contains current icon image.
+  gfx::ImageSkia image_skia_;
+
+  std::unique_ptr<extensions::IconImage> icon_;
+
+  DISALLOW_COPY_AND_ASSIGN(ExtensionAppIcon);
+};
+
+}  // namespace extensions
+
+#endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_APP_ICON_H_