Let SetEnv.cmd set VSINSTALLDIR, VCINSTALLDIR

win_toolchain/package_from_installed.py

 # Copyright 2014 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.
 
 """
 From a system-installed copy of the toolchain, packages all the required bits
 into a .zip file.
 
 It assumes default install locations for tools, in particular:
 - C:\Program Files (x86)\Microsoft Visual Studio 12.0\...
@@ skipping 165 matching lines @@
   """Generate a batch file that gyp expects to exist to set up the compiler
   environment.
 
   This is normally generated by a full install of the SDK, but we
   do it here manually since we do not do a full install."""
   with open(os.path.join(
         target_dir, r'win_sdk\bin\SetEnv.cmd'), 'w') as f:
     f.write('@echo off\n'
             ':: Generated by win_toolchain\\package_from_installed.py.\n'
             # Common to x86 and x64
+            'set VSINSTALLDIR=%~dp0..\\..\\\n'
+            'set VCINSTALLDIR=%~dp0..\\..\\VC\\\n'

[scottmg, 2016/01/20 20:50:24]

Yuck, these do have trailing \ in vcvarsall. :(

             'set PATH=%~dp0..\\..\\Common7\\IDE;%PATH%\n'
             'set INCLUDE=%~dp0..\\..\\win_sdk\\Include\\WINVERSION\\um;'
                '%~dp0..\\..\\win_sdk\\Include\\WINVERSION\\shared;'
                '%~dp0..\\..\\win_sdk\\Include\\WINVERSION\\winrt;'
                '%~dp0..\\..\\win_sdk\\Include\\WINVERSION\\ucrt;' # VS 2015
                '%~dp0..\\..\\VC\\include;'
                '%~dp0..\\..\\VC\\atlmfc\\include\n'
             'if "%1"=="/x64" goto x64\n'.replace('WINVERSION', WIN_VERSION))
 
     # x86. Always use amd64_x86 cross, not x86 on x86.
@@ skipping 121 matching lines @@
   sys.stdout.write('\rWrote to %s.%s\n' % (output, ' '*50))
   sys.stdout.flush()
 
   RenameToSha1(output)
 
   return 0
 
 
 if __name__ == '__main__':
   sys.exit(main())