I followed your (otherwise excellent) windows_build_instructions.md precisely, but end up as below.

The step (whatever it is; I'm not sure; it's not obvious) needed to prepare VC for building chromium needs adding into the instructions:


C:\src\chromium\src>gn gen out/Default
Traceback (most recent call last):
  File "C:/src/chromium/src/build/toolchain/win/setup_toolchain.py", line 202, in <module>
    main()
  File "C:/src/chromium/src/build/toolchain/win/setup_toolchain.py", line 170, in main
    env = _LoadToolchainEnv(cpu, win_sdk_path)
  File "C:/src/chromium/src/build/toolchain/win/setup_toolchain.py", line 131, in _LoadToolchainEnv
    script_path)
Exception: C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\vcvarsall.bat is missing - make sure VC++ tools are installed.
ERROR at //build/toolchain/win/BUILD.gn:365:22: Script returned non-zero exit code.
x64_toolchain_data = exec_script("setup_toolchain.py",
                     ^----------
Current dir: C:/src/chromium/src/out/Default/
Command: C:/src/depot_tools/python276_bin/python.exe -- C:/src/chromium/src/build/toolchain/win/setup_toolchain.py "C:\Program Files (x86)\Microsoft Visual Studio 14.0" "C:\Program Files (x86)\Windows Kits\10" "C:\Windows\Sysnative;C:\Windows\SysWOW64" x64 /I
Returned 1.
See //BUILD.gn:74:1: which caused the file to be included.
group("gn_all") {
^----------------


C:\src\chromium\src>cd \

C:\>dir /s /a vcvarsall.bat
 Volume in drive C has no label.
 Volume Serial Number is 52AE-546D
File Not Found