[GN] Allow Xcode source indexing of non default files.

BUG=

Review-Url: https://codereview.chromium.org/2086463002
Cr-Original-Commit-Position: refs/heads/master@{#400919}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 7b90a1de5ac82360dcffce82744d6de866cb73ba
diff --git a/tools/gn/xcode_writer.cc b/tools/gn/xcode_writer.cc
index 10624fa..e076339 100644
--- a/tools/gn/xcode_writer.cc
+++ b/tools/gn/xcode_writer.cc
@@ -325,9 +325,6 @@
     TargetOsType target_os) {
   std::vector<SourceFile> sources;
   for (const Target* target : targets) {
-    if (!target->settings()->is_default())
-      continue;
-
     for (const SourceFile& source : target->sources()) {
       if (source.is_system_absolute())
         continue;