Version: Chromium master revision 318e6f54 (#400326)
OS: Mac

What steps will reproduce the problem?
(1) As part of defining multiple mac_app_bundle targets in the same BUILD.gn file define multiple mac_xib_bundle_data targets that use the same xib file name (see below).

What is the expected output?
The `gn gen` should succeed.

What do you see instead?
The `gn gen` fails due to multiple targets with the same output.

Please use labels and text to provide additional information.

The compile_xibs template currently uses an output path of "$target_gen_dir/{{source_name_part}}.nib". This means the following in the same BUILD.gn file will fail:

mac_xib_bundle_data("app1_xibs") {
  sources = [
    "app1/English.lproj/MainMenu.xib",
  ]

  output_path = "{{bundle_resources_dir}}/English.lproj"
}

mac_xib_bundle_data("app2_xibs") {
  sources = [
    "app2/English.lproj/MainMenu.xib",
  ]

  output_path = "{{bundle_resources_dir}}/English.lproj"
}

The compile_xibs template should probably be modified to use a unique output path. For example:

diff --git a/build/config/mac/base_rules.gni b/build/config/mac/base_rules.gni
index 76610cc..7d17aba 100644
--- a/build/config/mac/base_rules.gni
+++ b/build/config/mac/base_rules.gni
@@ -366,13 +366,13 @@ template("compile_xibs") {
     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"),
+             rebase_path("$target_gen_dir/$target_name/{{source_name_part}}.nib"),
            ] + ibtool_flags
   }
 }