Change NotifyAppList*() functions into observers on a ProfileKeyedService.

chrome/browser/extensions/install_observer.h

+// Copyright 2013 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_INSTALL_OBSERVER_H_
+#define CHROME_BROWSER_EXTENSIONS_INSTALL_OBSERVER_H_
+
+namespace gfx {
+class ImageSkia;
+}
+
+namespace extensions {
+
+class InstallObserver {
+ public:
+  virtual void OnBeginExtensionInstall(
+      const std::string& extension_id,
+      const std::string& extension_name,
+      const gfx::ImageSkia& installing_icon,
+      bool is_app) = 0;
+
+  virtual void OnDownloadProgress(const std::string& extension_id,
+                                  int percent_downloaded) = 0;
+
+  virtual void OnInstallFailure(const std::string& extension_id) = 0;
+
+ protected:
+  virtual ~InstallObserver() {}
+};
+
+}  // namespace extensions
+
+#endif  // CHROME_BROWSER_EXTENSIONS_INSTALL_OBSERVER_H_