Make shelf web app context menu launch container based on user preference

This CL fixes the web app shelf context menu to say new window/tab based
on the user's launch preference rather than the app's display mode.

Before:
https://bugs.chromium.org/p/chromium/issues/attachment?aid=458355&signed_aid=aSdrvahZRLm3LzIlT4Lw_Q==&inline=1
After:
https://bugs.chromium.org/p/chromium/issues/attachment?aid=458354&signed_aid=mhKi9zbHVVMVIsNjtGjytQ==&inline=1

Bug: 1100016
Change-Id: I7c488be8e78fc76a73b5fd95d1d40bdcf137778e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2319928
Auto-Submit: Alan Cutter <alancutter@chromium.org>
Reviewed-by: Nancy Wang <nancylingwang@chromium.org>
Commit-Queue: Alan Cutter <alancutter@chromium.org>
Cr-Commit-Position: refs/heads/master@{#791732}

chrome/browser/apps/app_service/web_apps_chromeos.cc

@@ -207,7 +207,7 @@ void WebAppsChromeOs::GetMenuModel(const std::string& app_id,
   if (!is_system_web_app) {
     CreateOpenNewSubmenu(
         menu_type,
-        web_app->display_mode() == web_app::DisplayMode::kStandalone
+        web_app->user_display_mode() == web_app::DisplayMode::kStandalone
             ? IDS_APP_LIST_CONTEXT_MENU_NEW_WINDOW
             : IDS_APP_LIST_CONTEXT_MENU_NEW_TAB,
         &menu_items);