cbui: don't show buttons on translate bubble

There was an error in 74eb4979,
which removed this DialogDelegate's GetDialogButtons override but
didn't add a matching set_buttons call.

TBR=pbos@chromium.org

Bug: 1024761
Change-Id: I085c89d0fbaecaa442d7f8036b31ef2b17b20130
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1917239Reviewed-by: Elly Fong-Jones <ellyjones@chromium.org>
Commit-Queue: Elly Fong-Jones <ellyjones@chromium.org>
Cr-Commit-Position: refs/heads/master@{#715288}

chrome/browser/ui/views/translate/translate_bubble_view.cc

@@ -654,6 +654,7 @@ TranslateBubbleView::TranslateBubbleView(
   if (web_contents)  // web_contents can be null in unit_tests.
     mouse_handler_ =
         std::make_unique<WebContentMouseHandler>(this, web_contents);
+  DialogDelegate::set_buttons(ui::DIALOG_BUTTON_NONE);
   DialogDelegate::SetFootnoteView(CreateWordmarkView(bubble_ui_model_));
   chrome::RecordDialogCreation(chrome::DialogIdentifier::TRANSLATE);
 }