WebApp: Fix migration of user display mode.

Bug: 1059163
Change-Id: If4225068704930421a126b71f37c35133da006d1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2091171Reviewed-by: Alan Cutter <alancutter@chromium.org>
Reviewed-by: Eric Willigers <ericwilligers@chromium.org>
Commit-Queue: Eric Willigers <ericwilligers@chromium.org>
Cr-Commit-Position: refs/heads/master@{#747653}

chrome/browser/web_applications/web_app_migration_manager.cc

@@ -180,8 +180,12 @@ std::unique_ptr<WebApp> WebAppMigrationManager::MigrateBookmarkApp(
 
   web_app->SetThemeColor(bookmark_app_registrar_.GetAppThemeColor(app_id));
   web_app->SetDisplayMode(bookmark_app_registrar_.GetAppDisplayMode(app_id));
-  web_app->SetUserDisplayMode(
-      bookmark_app_registrar_.GetAppUserDisplayMode(app_id));
+
+  DisplayMode user_display_mode =
+      bookmark_app_registrar_.GetAppUserDisplayMode(app_id);
+  if (user_display_mode != DisplayMode::kUndefined)
+    web_app->SetUserDisplayMode(user_display_mode);
+
   web_app->SetIsLocallyInstalled(
       bookmark_app_registrar_.IsLocallyInstalled(app_id));
   web_app->SetIconInfos(bookmark_app_registrar_.GetAppIconInfos(app_id));