Made it possible to tell whether an extension is being installed or updated.

chrome/browser/chromeos/screensaver/screensaver_controller.cc

 // Copyright (c) 2012 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/chromeos/screensaver/screensaver_controller.h"
 
 #include "ash/screensaver/screensaver_view.h"
 #include "ash/shell.h"
 #include "ash/wm/user_activity_detector.h"
 #include "base/bind.h"
@@ skipping 85 matching lines @@
   TeardownScreensaver();
 }
 
 void ScreensaverController::Observe(
     int type,
     const content::NotificationSource& source,
     const content::NotificationDetails& details) {
   switch (type) {
     case chrome::NOTIFICATION_EXTENSION_INSTALLED: {
       const extensions::Extension* extension =
-          content::Details<const extensions::Extension>(details).ptr();
+          content::Details<const extensions::InstalledExtensionInfo>(details)->
+              extension;
       // Uninstall any previously installed screensaver extensions if a new
       // screensaver extension is installed.
       if (extension->HasAPIPermission(extensions::APIPermission::kScreensaver))
         UninstallPreviousScreensavers(extension);
       break;
     }
     case chrome::NOTIFICATION_EXTENSION_LOADED: {
       const extensions::Extension* extension =
           content::Details<const extensions::Extension>(details).ptr();
       if (extension->HasAPIPermission(extensions::APIPermission::kScreensaver))
@@ skipping 58 matching lines @@
   ash::CloseScreensaver();
   screensaver_extension_id_ = "";
 }
 
 void ScreensaverController::RequestNextIdleNotification() {
   DBusThreadManager::Get()->GetPowerManagerClient()->
       RequestIdleNotification(threshold_.InMilliseconds());
 }
 
 }  // namespace chromeos