Don't show system notifications while the screen is locked.

chrome/browser/chromeos/extensions/file_browser_notifications_browsertest.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/extensions/file_browser_notifications.h"
 
 #include <gtest/gtest.h>
 #include <string>
 
 #include "chrome/browser/browser_process.h"
@@ skipping 58 matching lines @@
     std::string path;
   };
 
   HideCallbackData hide_callback_data_;
 };
 
 class FileBrowserNotificationsTest : public InProcessBrowserTest {
  public:
   FileBrowserNotificationsTest() : collection_(NULL) {}
 
+  virtual void CleanUpOnMainThread() OVERRIDE {
+    notifications_.reset();
+  }
+
  protected:
   // This must be initialized late in test startup.
   void InitNotifications() {
     Profile* profile = browser()->profile();
     notifications_.reset(new MockFileBrowserNotifications(profile));
     collection_ =
         g_browser_process->notification_ui_manager()->balloon_collection();
   }
 
   bool FindNotification(const std::string& id) {
@@ skipping 147 matching lines @@
 
   // Delayed hide for a notification that doesn't exist does nothing.
   notifications_->HideNotificationDelayed(FileBrowserNotifications::DEVICE_FAIL,
                                           "path", 3000);
   notifications_->ExecuteHide();
   ui_test_utils::RunAllPendingInMessageLoop();
   EXPECT_EQ(0u, collection_->GetActiveBalloons().size());
 }
 
 }  // namespace chromeos.