Consolidate some more ash tray constants.

ash/common/system/chromeos/audio/volume_view.cc

 // Copyright 2014 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/audio/volume_view.h"
 
 #include <algorithm>
 
 #include "ash/common/metrics/user_metrics_action.h"
 #include "ash/common/strings/grit/ash_strings.h"
@@ skipping 114 matching lines @@
 
   if (!is_default_view_) {
     tri_view_->SetContainerVisible(TriView::Container::END, false);
     Update();
     return;
   }
 
   more_button_ = new ButtonListenerActionableView(
       owner_, TrayPopupInkDropStyle::INSET_BOUNDS, this);
   TrayPopupUtils::ConfigureContainer(TriView::Container::END, more_button_);
+
   more_button_->SetInkDropMode(views::InkDropHostView::InkDropMode::ON);
   more_button_->SetBorder(views::CreateEmptyBorder(gfx::Insets(
-      0, GetTrayConstant(TRAY_POPUP_ITEM_MORE_REGION_HORIZONTAL_INSET))));
+      0, kTrayPopupButtonEndMargin)));
   tri_view_->AddView(TriView::Container::END, more_button_);
 
   device_type_ = TrayPopupUtils::CreateMoreImageView();
   device_type_->SetVisible(false);
   more_button_->AddChildView(device_type_);
 
   more_button_->AddChildView(TrayPopupUtils::CreateMoreImageView());
 
   Update();
 }
@@ skipping 90 matching lines @@
     if (new_volume > current_volume)
       HandleVolumeUp(new_volume);
     else
       HandleVolumeDown(new_volume);
   }
   icon_->Update();
 }
 
 }  // namespace tray
 }  // namespace ash