Added Ash.SystemMenu.DefaultView.VisibleItems histogram.

ash/common/system/chromeos/bluetooth/tray_bluetooth.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/chromeos/bluetooth/tray_bluetooth.h"
 
 #include "ash/common/session/session_state_delegate.h"
 #include "ash/common/system/tray/fixed_sized_scroll_view.h"
 #include "ash/common/system/tray/hover_highlight_view.h"
 #include "ash/common/system/tray/system_tray.h"
@@ skipping 376 matching lines @@
   BluetoothDeviceList connecting_devices_;
   BluetoothDeviceList paired_not_connected_devices_;
   BluetoothDeviceList discovered_not_paired_devices_;
 
   DISALLOW_COPY_AND_ASSIGN(BluetoothDetailedView);
 };
 
 }  // namespace tray
 
 TrayBluetooth::TrayBluetooth(SystemTray* system_tray)
-    : SystemTrayItem(system_tray), default_(NULL), detailed_(NULL) {
+    : SystemTrayItem(system_tray, UMA_BLUETOOTH),
+      default_(nullptr),
+      detailed_(nullptr) {
   WmShell::Get()->system_tray_notifier()->AddBluetoothObserver(this);
 }
 
 TrayBluetooth::~TrayBluetooth() {
   WmShell::Get()->system_tray_notifier()->RemoveBluetoothObserver(this);
 }
 
 views::View* TrayBluetooth::CreateTrayView(LoginStatus status) {
   return NULL;
 }
@@ skipping 35 matching lines @@
     detailed_->Update();
 }
 
 void TrayBluetooth::OnBluetoothDiscoveringChanged() {
   if (!detailed_)
     return;
   detailed_->Update();
 }
 
 }  // namespace ash