GN Throwing Errors When Creating Build dir For Chromium

Question

I am trying to create a build directory on my Windows 10 Laptop using GN for Chromium source code. This is what I have done:

1. Set a WIN TOOLCHAIN system environment variable and set it to 0
2. Append C:\src\depot_tools to my system Path variable - C:\src\depot_tools\src is where the source code is
3. Download a working GN.exe binary and place it in the same folder with GN.exe.sha1, which is in C:\src\depot_tools\src\buildtools\win

I try to run gn gen out\Default but then this keeps getting thrown-

    gn gen out\Default
Traceback (most recent call last):
  File "c:/src/depot_tools/src/build/vs_toolchain.py", line 493, in <module>
    sys.exit(main())
  File "c:/src/depot_tools/src/build/vs_toolchain.py", line 489, in main
    return commands[sys.argv[1]](*sys.argv[2:])
  File "c:/src/depot_tools/src/build/vs_toolchain.py", line 312, in CopyDlls
    _CopyRuntime(target_dir, runtime_dir, target_cpu, debug=True)
  File "c:/src/depot_tools/src/build/vs_toolchain.py", line 292, in _CopyRuntime
    suffix)
  File "c:/src/depot_tools/src/build/vs_toolchain.py", line 206, in _CopyUCRTRuntime
    _CopyRuntimeImpl(target, source)
  File "c:/src/depot_tools/src/build/vs_toolchain.py", line 193, in _CopyRuntimeImpl
    shutil.copy2(source, target)
  File "C:\src\depot_tools\win_tools-2_7_6_bin\python\bin\lib\shutil.py", line 130, in copy2
    copyfile(src, dst)
  File "C:\src\depot_tools\win_tools-2_7_6_bin\python\bin\lib\shutil.py", line 82, in copyfile
    with open(src, 'rb') as fsrc:
IOError: [Errno 2] No such file or directory: 'C:\\Windows\\Sysnative\\msvcp140d.dll'
ERROR at //build/toolchain/win/BUILD.gn:43:3: Script returned non-zero exit code.
  exec_script("../../vs_toolchain.py",
  ^----------
Current dir: c:/src/depot_tools/src/out/Default/
Command: C:/src/depot_tools/win_tools-2_7_6_bin/python/bin/python.exe -- c:/src/depot_tools/src/build/vs_toolchain.py copy_dlls c:/src/depot_tools/src/out/Default Debug x64
Returned 1 and printed out:

Copying C:\Windows\Sysnative\ucrtbase.dll to c:/src/depot_tools/src/out/Default\ucrtbase.dll...
Copying C:\Windows\Sysnative\msvcp140d.dll to c:/src/depot_tools/src/out/Default\msvcp140d.dll...

See //BUILD.gn:69:1: which caused the file to be included.
group("gn_all") {
^----------------