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

ash/system/ime_menu/ime_list_view.cc

Index: ash/system/ime_menu/ime_list_view.cc
diff --git a/ash/system/ime_menu/ime_list_view.cc b/ash/system/ime_menu/ime_list_view.cc
index 2fa68acd4e6b8de091af0eaad4f02ab9557f2354..98338116d83d945f49ad7e043c2da33586d8988d 100644
--- a/ash/system/ime_menu/ime_list_view.cc
+++ b/ash/system/ime_menu/ime_list_view.cc
@@ -309,11 +309,11 @@ void ImeListView::HandleViewClicked(views::View* view) {
 
 void ImeListView::HandleButtonPressed(views::Button* sender,
                                       const ui::Event& event) {
-  if (keyboard_status_row_ && sender == keyboard_status_row_->toggle()) {
-    ShellPort::Get()->ToggleIgnoreExternalKeyboard();
-    last_selected_item_id_.clear();
-    last_item_selected_with_keyboard_ = false;
-  }
+  DCHECK_EQ(sender, keyboard_status_row_->toggle());
+
+  ShellPort::Get()->ToggleIgnoreExternalKeyboard();
+  last_selected_item_id_.clear();
+  last_item_selected_with_keyboard_ = false;
 }
 
 void ImeListView::VisibilityChanged(View* starting_from, bool is_visible) {