Use new toolchain_args variable in GN

build/toolchain/cc_wrapper.gni

 # Copyright (c) 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/toolchain/goma.gni")
+
 # Defines the configuration of cc wrapper
 # ccache: a c/c++ compiler cache which can greatly reduce recompilation times.
 # icecc, distcc: it takes compile jobs from a build and distributes them among
 #                remote machines allowing a parallel build.
 #
 # TIPS
 #
 # 1) ccache
 # Set clang_use_chrome_plugins=false if using ccache 3.1.9 or earlier, since
 # these versions don't support -Xclang.  (3.1.10 and later will silently
@@ skipping 11 matching lines @@
 # Set clang_use_chrome_plugins=false because icecc cannot distribute custom
 # clang libraries.
 #
 # To use icecc and ccache together, set cc_wrapper = "ccache" with
 # export CCACHE_PREFIX=icecc
 
 declare_args() {
   # Set to "ccache", "icecc" or "distcc".  Probably doesn't work on windows.
   cc_wrapper = ""
 }
+
+assert(!use_goma || cc_wrapper == "",
+       "use_goma and cc_wrapper can not be used together.")