Fix errors found in Mac gn component builds

sandbox/mac/BUILD.gn

 # Copyright 2014 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.
 
 import("//build/config/mac/mac_sdk.gni")
 import("//testing/test.gni")
 
 component("sandbox") {
   sources = [
     "bootstrap_sandbox.cc",
@@ skipping 21 matching lines @@
   deps = [
     "//base",
   ]
 
   # When the build SDK is 10.6, generate a dynamic stub loader. When the
   # SDK is higher, then libxpc.dylib will be loaded automatically as part
   # of libSystem, and only forward declarations of private symbols are
   # necessary.
   if (mac_sdk_version == "10.6") {
     deps += [ ":generate_stubs" ]
+    sources += get_target_outputs(":generate_stubs")
   }
 }
 
 generate_stubs_script = "//tools/generate_stubs/generate_stubs.py"
 generate_stubs_header = "xpc_stubs_header.fragment"
 generate_stubs_sig_public = "xpc_stubs.sig"
 generate_stubs_sig_private = "xpc_private_stubs.sig"
 generate_stubs_project = "sandbox/mac"
 generate_stubs_output_stem = "xpc_stubs"
 
@@ skipping 42 matching lines @@
     "Foundation.framework",
   ]
 
   deps = [
     ":sandbox",
     "//base",
     "//base/test:run_all_unittests",
     "//testing/gtest",
   ]
 }