Work on Mac GN build

build/toolchain/mac/BUILD.gn

 # Copyright (c) 2013 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.
 
 # TODO(brettw) Use "gcc_toolchain.gni" like the Linux toolchains. This requires
 # some enhancements since the commands on Mac are slightly different than on
 # Linux.
 
 import("../goma.gni")
 
 # Should only be running on Mac.
 assert(is_mac || is_ios)
 
 import("//build/toolchain/clang.gni")
 import("//build/toolchain/goma.gni")
 
 if (is_clang) {
   cc = rebase_path("//third_party/llvm-build/Release+Asserts/bin/clang",
                    root_build_dir)
   cxx = rebase_path("//third_party/llvm-build/Release+Asserts/bin/clang++",
                     root_build_dir)
-
-  # Set the GYP header for all toolchains when running under Clang.
-  if (is_gyp) {
-    make_global_settings = make_clang_global_settings
-
-    if (use_goma) {
-      # There is a TODO(yyanagisawa) in common.gypi about the make generator not
-      # supporting CC_wrapper without CC. As a result, we must add a condition
-      # when on the generator when we're not explicitly setting the variables
-      # above (which happens when gyp_header is empty at this point).
-      #
-      # GYP will interpret the file once for each generator, so we have to write
-      # this condition into the GYP file since the user could have more than one
-      # generator set.
-      gyp_header =
-        "'conditions':" +
-        "[['\"<(GENERATOR)\"==\"ninja\"', { 'make_global_settings': [" +
-        make_global_settings +
-        make_goma_global_settings +
-        "]}]],"
-    } else {
-      gyp_header = "'make_global_settings': [" + make_global_settings + "],"
-    }
-  }
 } else {
   cc = "gcc"
   cxx = "g++"
 }
 ld = cxx
 
 # This will copy the gyp-mac-tool to the build directory. We pass in the source
 # file of the win tool.
 gyp_mac_tool_source =
   rebase_path("//tools/gyp/pylib/gyp/mac_tool.py", root_build_dir)
@@ skipping 92 matching lines @@
 # Toolchain representing the target build (either mac or iOS).
 mac_clang_toolchain("clang") {
   toolchain_os = os
 }
 
 # This toolchain provides a way for iOS target compiles to reference targets
 # compiled for the host system. It just overrides the OS back to "mac".
 mac_clang_toolchain("host_clang") {
   toolchain_os = "mac"
 }