UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/54.0.2840.71 Safari/537.36

Steps to reproduce the problem:
1. Pull chromium 54.0.2840.98 
2. Build
3. 

What is the expected behavior?
Completed Build

What went wrong?
/Volumes/hd2/src/chromium/src/buildtools/mac/gn --root=/Volumes/hd2/src/chromium/src -q gen //out/Default/
ERROR at //build/toolchain/nacl_toolchain.gni:41:30: Clobbering existing value.
                             "is_clang",
                             ^---------
The current scope already defines a value "is_clang".
forward_variables_from() won't clobber existing values. If you want to
merge lists, you'll need to do this explicitly.
See //build/config/BUILDCONFIG.gn:125:14: value being clobbered.
  is_clang = current_os == "mac" || current_os == "ios" ||
             ^--------------------------------------------
See //build/toolchain/nacl/BUILD.gn:63:3: whence it was called.
  nacl_toolchain(target_name) {
  ^----------------------------
See //build/toolchain/nacl/BUILD.gn:89:1: whence it was called.
pnacl_toolchain("newlib_pnacl") {
^--------------------------------
See //ppapi/BUILD.gn:385:7: which caused the file to be included.
      ":ppapi_nacl_tests_copy(//build/toolchain/nacl:clang_newlib_${target_cpu})",
      ^--------------------------------------------------------------------------
ninja: error: rebuilding 'build.ninja': subcommand failed

Did this work before? Yes 54.0.2840.71

Chrome version: 54.0.2840.98  Channel: stable
OS Version: OS X 10.12.1
Flash Version: Shockwave Flash 23.0 r0