Added Ash.SystemMenu.DefaultView.VisibleItems histogram.

ash/common/system/chromeos/brightness/tray_brightness.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 "ash/common/system/chromeos/brightness/tray_brightness.h"
 
 #include <algorithm>
 
 #include "ash/common/ash_constants.h"
 #include "ash/common/shell_observer.h"
@@ skipping 153 matching lines @@
 
 void BrightnessView::SliderDragEnded(views::Slider* slider) {
   DCHECK_EQ(slider, slider_);
   dragging_ = false;
   slider_->SetValue(static_cast<float>(last_percent_ / 100.0));
 }
 
 }  // namespace tray
 
 TrayBrightness::TrayBrightness(SystemTray* system_tray)
-    : SystemTrayItem(system_tray),
+    : SystemTrayItem(system_tray, UMA_DISPLAY_BRIGHTNESS),
       brightness_view_(NULL),
       current_percent_(100.0),
       got_current_percent_(false),
       weak_ptr_factory_(this) {
   // Post a task to get the initial brightness; the BrightnessControlDelegate
   // isn't created yet.
   base::ThreadTaskRunnerHandle::Get()->PostTask(
       FROM_HERE, base::Bind(&TrayBrightness::GetInitialBrightness,
                             weak_ptr_factory_.GetWeakPtr()));
   chromeos::DBusThreadManager::Get()->GetPowerManagerClient()->AddObserver(
@@ skipping 84 matching lines @@
   if (!display::Display::HasInternalDisplay())
     return;
 
   if (brightness_view_)
     SetDetailedViewCloseDelay(kTrayPopupAutoCloseDelayInSeconds);
   else
     PopupDetailedView(kTrayPopupAutoCloseDelayInSeconds, false);
 }
 
 }  // namespace ash