Mac: Use unique output path for compile_xibs template in GN

build/config/mac/base_rules.gni

 # Copyright 2016 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # This file contains rules that are shared between Mac and iOS.
 
 import("//build/toolchain/toolchain.gni")
 
 if (is_mac) {
   import("//build/config/mac/mac_sdk.gni")
@@ skipping 348 matching lines @@
            "Sources must be specified for $target_name")
 
     ibtool_flags = []
     if (defined(invoker.ibtool_flags)) {
       ibtool_flags = invoker.ibtool_flags
     }
 
     script = "//build/config/mac/compile_xib.py"
     sources = invoker.sources
     outputs = [
-      "$target_gen_dir/{{source_name_part}}.nib",
+      "$target_gen_dir/$target_name/{{source_name_part}}.nib",
     ]
-    args = [
-             "--input",
-             "{{source}}",
-             "--output",
-             rebase_path("$target_gen_dir/{{source_name_part}}.nib"),
-           ] + ibtool_flags
+    args =
+        [
+          "--input",
+          "{{source}}",
+          "--output",
+          rebase_path("$target_gen_dir/$target_name/{{source_name_part}}.nib"),
+        ] + ibtool_flags
   }
 }