Clean up unnecessary variable 'error' in GetLoginItemForApp

LSSharedFileListItemCopyResolvedURL can operate with nullptr as its
CFErrorRef* argument. We can just check if it returned a non-null
CFURLRef, and simplify this code.

Tested: Manually on MacOS 11.0
 - Install extension from chrome/test/data/extensions/background_app/
 - Chromium should be set to run at login for user
 - Remove extension - chromium should no longer be set to run at login

Bug: 897302
Change-Id: If673ec9a53e99fcebe910e34ec50d88594debd39
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2561032
Commit-Queue: Mike Jackson <mjackson@microsoft.com>
Reviewed-by: Mark Mentovai <mark@chromium.org>
Reviewed-by: Victor Costan <pwnall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#832601}

base/mac/mac_util.mm

@@ -67,20 +67,12 @@ class LoginItemsFileList {
     for (id login_item in login_items_array.get()) {
       LSSharedFileListItemRef item =
           reinterpret_cast<LSSharedFileListItemRef>(login_item);
-      base::ScopedCFTypeRef<CFErrorRef> error;
       ScopedCFTypeRef<CFURLRef> item_url(
-          LSSharedFileListItemCopyResolvedURL(item, 0, error.InitializeInto()));
-
-      // This function previously used LSSharedFileListItemResolve(), which
-      // could return a NULL URL even when returning no error. This caused
-      // <https://crbug.com/760989>. It's not clear one way or the other whether
-      // LSSharedFileListItemCopyResolvedURL() shares this behavior, so this
-      // check remains in place.
-      if (!error && item_url) {
-        if (CFEqual(item_url, url)) {
-          return ScopedCFTypeRef<LSSharedFileListItemRef>(
-              item, base::scoped_policy::RETAIN);
-        }
+          LSSharedFileListItemCopyResolvedURL(item, 0, nullptr));
+
+      if (item_url && CFEqual(item_url, url)) {
+        return ScopedCFTypeRef<LSSharedFileListItemRef>(
+            item, base::scoped_policy::RETAIN);
       }
     }