Remove TrayPopupLabelButton (a pre-MD class) and its assets.

ash/common/system/tray/tray_popup_utils.cc

 // Copyright 2016 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_popup_utils.h"
 
 #include <algorithm>
 #include <utility>
 
 #include "ash/common/ash_constants.h"
 #include "ash/common/ash_view_ids.h"
 #include "ash/common/material_design/material_design_controller.h"
 #include "ash/common/session/session_state_delegate.h"
 #include "ash/common/system/tray/fixed_sized_image_view.h"
 #include "ash/common/system/tray/size_range_layout.h"
 #include "ash/common/system/tray/tray_constants.h"
 #include "ash/common/system/tray/tray_popup_item_style.h"
-#include "ash/common/system/tray/tray_popup_label_button.h"
-#include "ash/common/system/tray/tray_popup_label_button_border.h"
 #include "ash/common/wm_shell.h"
 #include "base/memory/ptr_util.h"
 #include "ui/base/l10n/l10n_util.h"
 #include "ui/views/animation/flood_fill_ink_drop_ripple.h"
 #include "ui/views/animation/ink_drop_highlight.h"
 #include "ui/views/animation/ink_drop_impl.h"
 #include "ui/views/animation/ink_drop_mask.h"
 #include "ui/views/animation/square_ink_drop_ripple.h"
 #include "ui/views/background.h"
 #include "ui/views/border.h"
@@ skipping 415 matching lines @@
 bool TrayPopupUtils::CanOpenWebUISettings(LoginStatus status) {
   // TODO(tdanderson): Consider moving this into WmShell, or introduce a
   // CanShowSettings() method in each delegate type that has a
   // ShowSettings() method.
   return status != LoginStatus::NOT_LOGGED_IN &&
          status != LoginStatus::LOCKED &&
          !WmShell::Get()->GetSessionStateDelegate()->IsInSecondaryLoginScreen();
 }
 
 }  // namespace ash