Update Chomium's build files to work w/ latest GN binaries.

build/toolchain/gcc_toolchain.gni

 # 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.
 
 # This value will be inherited in the toolchain below.
 concurrent_links = exec_script("get_concurrent_links.py", [], "value")
 
 # This template defines a toolchain for something that works like gcc
 # (including clang).
 #
 # It requires the following variables specifying the executables to run:
 #  - cc
 #  - cxx
 #  - ar
 #  - ld
 # and the following which is used in the toolchain_args
-#  - toolchain_cpu_arch  (What "cpu_arch" should be set to when invoking a
-#                         build using this toolchain.)
-#  - toolchain_os  (What "os" should be set to when invoking a build using this
-#                   toolchain.)
+#  - toolchain_cpu  (What "current_cpu" should be set to when invoking a
+#                    build using this toolchain.)
+#  - toolchain_os  (What "current_os" should be set to when invoking a
+#                   build using this toolchain.)
 #
 # Optional parameters:
 #  - libs_section_prefix
 #  - libs_section_postfix
 #      The contents of these strings, if specified, will be placed around
 #      the libs section of the linker line. It allows one to inject libraries
 #      at the beginning and end for all targets in a toolchain.
 #  - solink_libs_section_prefix
 #  - solink_libs_section_postfix
 #      Same as libs_section_{pre,post}fix except used for solink instead of link.
@@ skipping 189 matching lines @@
       if (defined(invoker.is_clang)) {
         is_clang = invoker.is_clang
       }
     }
 
     if (defined(invoker.deps)) {
       deps = invoker.deps
     }
   }
 }