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

ash/system/ime/tray_ime_chromeos.cc

Index: ash/system/ime/tray_ime_chromeos.cc
diff --git a/ash/system/ime/tray_ime_chromeos.cc b/ash/system/ime/tray_ime_chromeos.cc
index 3ecbe7fbd3078da29e3ffe9068a71dbe42d2f235..ee3524b2ad6d6a742bf61bb42d0fcfdb79d4dd04 100644
--- a/ash/system/ime/tray_ime_chromeos.cc
+++ b/ash/system/ime/tray_ime_chromeos.cc
@@ -103,9 +103,10 @@ class IMEDetailedView : public ImeListView {
 
   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 {