[CrOS Wallpaper] Make Wallpaper Picker app searchable from Launcher

This improves discoverability of the app, which was previously only
available by clicking a link in settings or by right-clicking the
desktop.

Fixed: 1086197
Change-Id: Ia8037f3639ec33613cecef0aeb780b59b65cf5cc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2220337
Commit-Queue: Dominick Ng <dominickn@chromium.org>
Reviewed-by: Dominick Ng <dominickn@chromium.org>
Auto-Submit: Kyle Horimoto <khorimoto@chromium.org>
Cr-Commit-Position: refs/heads/master@{#772979}

chrome/browser/apps/app_service/extension_apps_base.cc

@@ -237,6 +237,15 @@ void ExtensionAppsBase::OnExtensionUninstalled(
 void ExtensionAppsBase::SetShowInFields(
     apps::mojom::AppPtr& app,
     const extensions::Extension* extension) {
+#if defined(OS_CHROMEOS)
+  if (extension->id() == extension_misc::kWallpaperManagerId) {
+    // Explicitly show the Wallpaper Picker app in search only.
+    app->show_in_launcher = apps::mojom::OptionalBool::kFalse;
+    app->show_in_search = apps::mojom::OptionalBool::kTrue;
+    app->show_in_management = apps::mojom::OptionalBool::kFalse;
+    return;
+  }
+#endif  // defined(OS_CHROMEOS)
   if (ShouldShow(extension, profile_)) {
     auto show = ShouldShownInLauncher(extension)
                     ? apps::mojom::OptionalBool::kTrue