desktop-pwas: Only check ENABLED extensions when installing new ones

BookmarkApps can only be ENABLED or inexistent, so it doesn't make sense
to query all extensions; querying ENABLED should be enough.

Bug: 916381
Change-Id: I232514d79a5a4413a6e400280b4e1eaec0f3da8c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1502314
Commit-Queue: Giovanni Ortuño Urquidi <ortuno@chromium.org>
Reviewed-by: Alexey Baskakov <loyso@chromium.org>
Cr-Commit-Position: refs/heads/master@{#637617}

chrome/browser/web_applications/extensions/bookmark_app_registrar.cc

@@ -26,8 +26,9 @@ void BookmarkAppRegistrar::Init(base::OnceClosure callback) {
 }
 
 bool BookmarkAppRegistrar::IsInstalled(const web_app::AppId& app_id) const {
-  return ExtensionRegistry::Get(profile_)->GetInstalledExtension(app_id) !=
-         nullptr;
+  auto* app =
+      ExtensionRegistry::Get(profile_)->enabled_extensions().GetByID(app_id);
+  return app != nullptr;
 }
 
 bool BookmarkAppRegistrar::WasExternalAppUninstalledByUser(