Add SessionStateObserver with ActiveUserChanged()

ash/system/user/tray_user_unittest.cc

 // 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.
 
 #include <vector>
 
 #include "ash/root_window_controller.h"
 #include "ash/shelf/shelf_layout_manager.h"
 #include "ash/shell.h"
 #include "ash/shell_delegate.h"
@@ skipping 122 matching lines @@
   ShowTrayMenu(&generator);
 
   EXPECT_TRUE(tray()->HasSystemBubble());
   EXPECT_TRUE(tray()->IsAnyBubbleVisible());
 
   for (int i = 0; i <= delegate()->GetMaximumNumberOfLoggedInUsers(); i++)
     EXPECT_EQ(i == 0 ? ash::internal::TrayUser::SHOWN :
                        ash::internal::TrayUser::HIDDEN,
               tray_user(i)->GetStateForTest());
 
-  tray()->CloseSystemBubbleForTest();
+  tray()->CloseSystemBubble();
 }
 
 // Make sure that in multi user mode the user panel can be activated and there
 // will be one panel for each user plus a separator.
 // Note: the mouse watcher (for automatic closing upon leave) cannot be tested
 // here since it does not work with the event system in unit tests.
 TEST_F(TrayUserTest, MutiUserModeDoesNotAllowToAddUser) {
   InitializeParameters(1, true);
 
   // Move the mouse over the status area and click to open the status menu.
@@ skipping 46 matching lines @@
                   ash::internal::TrayUser::ACTIVE_BUT_DISABLED :
                   ash::internal::TrayUser::ACTIVE,
               tray_user(0)->GetStateForTest());
 
     // Click the button again to see that the menu goes away.
     ClickUserItem(&generator, 0);
     EXPECT_EQ(ash::internal::TrayUser::HOVERED,
               tray_user(0)->GetStateForTest());
 
     // Close and check that everything is deleted.
-    tray()->CloseSystemBubbleForTest();
+    tray()->CloseSystemBubble();
     EXPECT_FALSE(tray()->IsAnyBubbleVisible());
     for (int i = 0; i < delegate()->GetMaximumNumberOfLoggedInUsers(); i++)
       EXPECT_EQ(ash::internal::TrayUser::HIDDEN,
                 tray_user(i)->GetStateForTest());
   }
 }
 
 // Make sure that user changing gets properly executed.
 TEST_F(TrayUserTest, MutiUserModeButtonClicks) {
   // Have two users.
   InitializeParameters(2, true);
   aura::test::EventGenerator generator(Shell::GetPrimaryRootWindow());
   ShowTrayMenu(&generator);
 
   // Switch to a new user.
   ClickUserItem(&generator, 1);
 
   EXPECT_EQ(delegate()->get_activated_user(), delegate()->GetUserEmail(1));
-  tray()->CloseSystemBubbleForTest();
+  tray()->CloseSystemBubble();
 }
 
 }  // namespace internal
 }  // namespace ash