Refactor extension app icon.

chrome/browser/extensions/chrome_app_icon_loader.cc

+// Copyright 2016 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/extensions/chrome_app_icon_loader.h"
+
+#include "base/stl_util.h"
+#include "chrome/browser/extensions/chrome_app_icon.h"
+#include "chrome/browser/extensions/chrome_app_icon_service.h"
+#include "chrome/browser/extensions/extension_service.h"
+#include "chrome/browser/extensions/extension_util.h"
+#include "chrome/browser/profiles/profile.h"
+#include "chrome/common/extensions/extension_constants.h"
+#include "extensions/browser/extension_system.h"
+#include "extensions/common/extension.h"
+#include "extensions/common/manifest_handlers/icons_handler.h"
+
+namespace extensions {
+
+namespace {
+
+const Extension* GetExtensionByID(Profile* profile, const std::string& id) {
+  ExtensionService* service =
+      ExtensionSystem::Get(profile)->extension_service();
+  if (!service)
+    return nullptr;
+  return service->GetInstalledExtension(id);
+}
+
+}  // namespace
+
+ChromeAppIconLoader::ChromeAppIconLoader(Profile* profile,
+                                         int icon_size,
+                                         AppIconLoaderDelegate* delegate)
+    : AppIconLoader(profile, icon_size, delegate) {}
+
+ChromeAppIconLoader::~ChromeAppIconLoader() {}
+
+bool ChromeAppIconLoader::CanLoadImageForApp(const std::string& id) {
+  if (map_.find(id) != map_.end())
+    return true;
+  return GetExtensionByID(profile(), id) != nullptr;
+}
+
+void ChromeAppIconLoader::FetchImage(const std::string& id) {
+  if (map_.find(id) != map_.end())
+    return;  // Already loading the image.
+
+  const Extension* extension = GetExtensionByID(profile(), id);
+  if (!extension)
+    return;
+
+  std::unique_ptr<ChromeAppIcon> icon =
+      ChromeAppIconService::Get(profile())->CreateIcon(this, id, icon_size());

[msw, 2017/05/03 01:17:39]

IT seems like the service does most of the actual loading, should
ChromeAppIconService inherit from AppIconLoader and then we could just remove
this class?

[khmel, 2017/05/03 02:15:22]

We still have ArcAppIconLoader which differs from this class conceptually and
base AppIconLoader to provide independent interface.

+
+  // Triggers image loading now instead of depending on paint message. This
+  // makes the temp blank image be shown for shorter time and improves user
+  // experience. See http://crbug.com/146114.
+  icon->EnsureRepsForSupportedScales();
+  map_[id] = std::move(icon);
+}
+
+void ChromeAppIconLoader::ClearImage(const std::string& id) {
+  map_.erase(id);
+}
+
+void ChromeAppIconLoader::UpdateImage(const std::string& id) {
+  ExtensionIDToImageMap::iterator it = map_.find(id);
+  if (it == map_.end())
+    return;
+
+  it->second->UpdateIcon();
+}
+
+void ChromeAppIconLoader::OnIconUpdated(ChromeAppIcon* icon) {
+  delegate()->OnAppImageUpdated(icon->app_id(), icon->image_skia());

[msw, 2017/05/03 01:17:39]

It's unfortunate that we have to go through two delegates here (this and
delegate())

[khmel, 2017/05/03 02:15:22]

This is legacy implementation and ArcAppIconLoader uses different scheme. Bug
agree, looks kind of redundant.

+}
+
+}  // namespace extensions