Added Ash.SystemMenu.DefaultView.VisibleItems histogram.

ash/common/system/tray/tray_empty.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/tray/tray_empty.h"
-
-#include "ui/views/background.h"
-#include "ui/views/border.h"
-#include "ui/views/layout/box_layout.h"
-#include "ui/views/view.h"
-
-namespace {
-
-class EmptyBackground : public views::Background {
- public:
-  EmptyBackground() {}
-  ~EmptyBackground() override {}
-
- private:
-  void Paint(gfx::Canvas* canvas, views::View* view) const override {}
-
-  DISALLOW_COPY_AND_ASSIGN(EmptyBackground);
-};
-}
-
-namespace ash {
-
-TrayEmpty::TrayEmpty(SystemTray* system_tray) : SystemTrayItem(system_tray) {}
-
-TrayEmpty::~TrayEmpty() {}
-
-views::View* TrayEmpty::CreateTrayView(LoginStatus status) {
-  return NULL;
-}
-
-views::View* TrayEmpty::CreateDefaultView(LoginStatus status) {
-  if (status == LoginStatus::NOT_LOGGED_IN)
-    return NULL;
-
-  views::View* view = new views::View;
-  view->set_background(new EmptyBackground());
-  view->SetBorder(views::Border::CreateEmptyBorder(10, 0, 0, 0));
-  view->SetLayoutManager(
-      new views::BoxLayout(views::BoxLayout::kVertical, 0, 0, 0));
-  view->SetPaintToLayer(true);
-  view->layer()->SetFillsBoundsOpaquely(false);
-  return view;
-}
-
-views::View* TrayEmpty::CreateDetailedView(LoginStatus status) {
-  return NULL;
-}
-
-void TrayEmpty::DestroyTrayView() {}
-
-void TrayEmpty::DestroyDefaultView() {}
-
-void TrayEmpty::DestroyDetailedView() {}
-
-void TrayEmpty::UpdateAfterLoginStatusChange(LoginStatus status) {}
-
-}  // namespace ash