Added Ash.SystemMenu.DefaultView.VisibleItems histogram.

ash/common/system/update/tray_update.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/update/tray_update.h"
 
 #include "ash/common/metrics/user_metrics_action.h"
 #include "ash/common/system/tray/fixed_sized_image_view.h"
 #include "ash/common/system/tray/system_tray.h"
 #include "ash/common/system/tray/system_tray_delegate.h"
@@ skipping 68 matching lines @@
         UMA_STATUS_AREA_OS_UPDATE_DEFAULT_SELECTED);
     return true;
   }
 
   DISALLOW_COPY_AND_ASSIGN(UpdateView);
 };
 
 }  // namespace
 
 TrayUpdate::TrayUpdate(SystemTray* system_tray)
-    : TrayImageItem(system_tray, IDR_AURA_UBER_TRAY_UPDATE) {
+    : TrayImageItem(system_tray, IDR_AURA_UBER_TRAY_UPDATE, UMA_UPDATE) {
   WmShell::Get()->system_tray_notifier()->AddUpdateObserver(this);
 }
 
 TrayUpdate::~TrayUpdate() {
   WmShell::Get()->system_tray_notifier()->RemoveUpdateObserver(this);
 }
 
 bool TrayUpdate::GetInitialVisibility() {
   UpdateInfo info;
   WmShell::Get()->system_tray_delegate()->GetSystemUpdateInfo(&info);
   return info.update_required;
 }
 
 views::View* TrayUpdate::CreateDefaultView(LoginStatus status) {
   UpdateInfo info;
   WmShell::Get()->system_tray_delegate()->GetSystemUpdateInfo(&info);
   return info.update_required ? new UpdateView(info) : nullptr;
 }
 
 void TrayUpdate::OnUpdateRecommended(const UpdateInfo& info) {
   SetImageFromResourceId(DecideResource(info.severity, false));
   tray_view()->SetVisible(true);
 }
 
 }  // namespace ash