[Ash] Use DCHECK in ImeListView::HandleButtonPressed()

ash/system/ime/tray_ime_chromeos.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/system/ime/tray_ime_chromeos.h"
 
 #include <vector>
 
 #include "ash/resources/vector_icons/vector_icons.h"
 #include "ash/session/session_state_delegate.h"
@@ skipping 85 matching lines @@
  private:
   // ImeListView:
   void ResetImeListView() override {
     ImeListView::ResetImeListView();
     settings_button_ = nullptr;
     controlled_setting_icon_ = nullptr;
   }
 
   void HandleButtonPressed(views::Button* sender,
                            const ui::Event& event) override {
-    ImeListView::HandleButtonPressed(sender, event);
     if (sender == settings_button_)
       ShowSettings();
+    else
+      ImeListView::HandleButtonPressed(sender, event);
   }
 
   void CreateExtraTitleRowButtons() override {
     if (!ime_managed_message_.empty()) {
       controlled_setting_icon_ = TrayPopupUtils::CreateMainImageView();
       controlled_setting_icon_->SetImage(
           gfx::CreateVectorIcon(kSystemMenuBusinessIcon, kMenuIconColor));
       controlled_setting_icon_->SetTooltipText(ime_managed_message_);
       tri_view()->AddView(TriView::Container::END, controlled_setting_icon_);
     }
@@ skipping 183 matching lines @@
   return ime_count >= threshold;
 }
 
 ImeListView::SingleImeBehavior TrayIME::GetSingleImeBehavior() {
   // If managed, we also want to show a single IME.
   return IsIMEManaged() ? ImeListView::SHOW_SINGLE_IME
                         : ImeListView::HIDE_SINGLE_IME;
 }
 
 }  // namespace ash