GN: Fix bootstrap call to setup_toolchain

The parameters to setup_toolchain changed, adding an OS parameter and a
filename for the environment file.

Additional fixes:
- Add missing base file to list of files
- vs_toolchain should output Windows paths properly escaped

Change-Id: I0e05bf34c8b603f16b901e76164e480121ed9d14
Reviewed-on: https://chromium-review.googlesource.com/1013926
Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Commit-Queue: Yngve Pettersen <yngve@vivaldi.com>
Cr-Original-Commit-Position: refs/heads/master@{#551341}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 95fe44b3c31cf5e1a668d9ef8853aaf2cf9523a5

tools/gn/bootstrap/bootstrap.py

diff --git a/tools/gn/bootstrap/bootstrap.py b/tools/gn/bootstrap/bootstrap.py
index bf0afb7..7fa9f04 100755
--- a/tools/gn/bootstrap/bootstrap.py
+++ b/tools/gn/bootstrap/bootstrap.py
@@ -129,7 +129,9 @@
        toolchain_paths["vs_path"],
        toolchain_paths["sdk_path"],
        toolchain_paths["runtime_dirs"],
+       "win",
        "x64",
+       "environment.x64",
        "true"
       ],
       cwd=tempdir)