Added Ash.SystemMenu.DefaultView.VisibleItems histogram.

ash/system/web_notification/web_notification_tray_unittest.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 "ash/common/system/web_notification/web_notification_tray.h"
 
 #include <utility>
 #include <vector>
 
 #include "ash/common/shelf/wm_shelf.h"
@@ skipping 51 matching lines @@
   return GetTray()->message_center();
 }
 
 SystemTray* GetSystemTray() {
   return StatusAreaWidgetTestHelper::GetStatusAreaWidget()->system_tray();
 }
 
 // Trivial item implementation for testing PopupAndSystemTray test case.
 class TestItem : public SystemTrayItem {
  public:
-  TestItem() : SystemTrayItem(GetSystemTray()) {}
+  TestItem() : SystemTrayItem(GetSystemTray(), UMA_TEST) {}
 
   views::View* CreateDefaultView(LoginStatus status) override {
     views::View* default_view = new views::View;
     default_view->SetLayoutManager(new views::FillLayout);
     default_view->AddChildView(new views::Label(base::UTF8ToUTF16("Default")));
     return default_view;
   }
 
   views::View* CreateNotificationView(LoginStatus status) override {
     return new views::View;
@@ skipping 439 matching lines @@
       ui::ET_TOUCH_RELEASED, out_of_bounds, touch_id,
       move.time_stamp() + base::TimeDelta::FromMilliseconds(50));
   generator.Dispatch(&release);
   EXPECT_FALSE(tray->draw_background_as_active());
   EXPECT_FALSE(tray->IsMessageCenterBubbleVisible());
 }
 
 #endif  // OS_CHROMEOS
 
 }  // namespace ash