More changes to support hermetic Xcode toolchain in GN.

third_party/WebKit/Source/platform/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/features.gni")
 import("//build/config/ui.gni")
 import("//testing/libfuzzer/fuzzer_test.gni")
 import("//testing/test.gni")
 import("//third_party/WebKit/Source/build/scripts/scripts.gni")
 import("//third_party/WebKit/Source/config.gni")
@@ skipping 110 matching lines @@
   color_data_gperf = "ColorData.gperf"
   inputs = [
     color_data_gperf,
   ]
 
   output_file = "$blink_platform_output_dir/ColorData.cpp"
   outputs = [
     output_file,
   ]
 
-  args = [
+  args = []
+  if (is_mac && !use_system_xcode) {
+    args += [
+      "--developer_dir",
+      hermetic_xcode_path,
+    ]
+  }
+
+  args += [
     gperf_exe,
     "--key-positions=*",
     "-D",
     "-s",
     "2",
     rebase_path(color_data_gperf, root_build_dir),
     "--output-file=" + rebase_path(output_file, root_build_dir),
   ]
 }
 
@@ skipping 1820 matching lines @@
     "//third_party/WebKit/Source:inside_blink",
   ]
 
   deps = [
     ":test_support",
     "//cc/surfaces:surface_id",
     "//testing/gmock",
     "//testing/gtest",
   ]
 }