Use new toolchain_args variable in GN

build/toolchain/cc_wrapper.gni

Index: build/toolchain/cc_wrapper.gni
diff --git a/build/toolchain/cc_wrapper.gni b/build/toolchain/cc_wrapper.gni
index 1fa185019ca0d44c71334d7528916719df2c38df..0a03dde8d62a20111828c8fec84f5f1557510281 100644
--- a/build/toolchain/cc_wrapper.gni
+++ b/build/toolchain/cc_wrapper.gni
@@ -2,6 +2,8 @@
 # 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
@@ -33,3 +35,6 @@ 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.")