GN Command line -D parsing, goma on Windows

build/toolchain/win/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.
 
+import("//build/toolchain/goma.gni")
+
 # Should only be running on Windows.
 assert(is_win)
 
 # Setup the Visual Studio state.
 #
 # Its argument is the location to write the environment files.
 # It will write "environment.x86" and "environment.x64" to this directory,
 # and return a list to us.
 #
 # The list contains the include path as its only element. (I'm expecting to
 # add more so it's currently a list inside a list.)
 #exec_script("get_msvc_config.py",
                      #     [relative_root_output_dir],
                      #     "value")
 
 # This will save the environment block and and copy the gyp-win-tool to the
 # build directory. We pass in the source file of the win tool.
 gyp_win_tool_source =
   rebase_path("//tools/gyp/pylib/gyp/win_tool.py", ".", root_build_dir)
 exec_script("setup_toolchain.py", [ gyp_win_tool_source ], "value")
 
 stamp_command = "$python_path gyp-win-tool stamp \$out"
 copy_command = "$python_path gyp-win-tool recursive-mirror \$in \$out"
 
+if (use_goma) {
+  # Add the Goma compiler prefixes to the GYP file.
+  gyp_header = make_goma_global_settings
+}
+
 # 32-bit toolchain -------------------------------------------------------------
 
 toolchain("32") {
   # Make these apply to all tools below.
   lib_prefix = ""
   lib_dir_prefix="/LIBPATH:"
 
   cc_command = "ninja -t msvc -e environment.x86 -- cl.exe /nologo /showIncludes /FC @\$out.rsp /c \$in /Fo\$out /Fd\$pdbname"
   tool("cc") {
     command = cc_command
@@ skipping 106 matching lines @@
 
   # When invoking this toolchain not as the default one, these args will be
   # passed to the build. They are ignored when this is the default toolchain.
   toolchain_args() {
     cpu_arch = "x64"
     # Normally the build config resets the CPU architecture to 32-bits. Setting
     # this flag overrides that behavior.
     force_win64 = true
   }
 }