This directory consumes tools from other repositories for use on the
bots. To update to newer revisions, follow these instructions:

DEPS: Set the external/gyp.git revision to the revision used in Chromium, found at
    https://chromium.googlesource.com/chromium/src/+/master/DEPS
    (Search for 'gyp.git'.)

go/bootstrap.py: Set TOOLSET_VERSION to the latest release of Go, found at
    https://golang.org/dl/.

update_clang.py: Set CLANG_REVISION and CLANG_SUB_REVISION to the values used in
    Chromium, found at
    https://chromium.googlesource.com/chromium/src/+/master/tools/clang/scripts/update.py

vs_toolchain.py: Set the hash in _GetDesiredVsToolchainHashes to the toolchain
    used in Chromium, found at
    https://chromium.googlesource.com/chromium/src/+/master/build/vs_toolchain.py
    This may require taking other updates to that file.

The .sha1 files correspond to files downloaded from Google Cloud Storage. To
update, place the updated files in their intended location and run:

    upload_to_google_storage.py -b chromium-tools FILE

cmake-linux64.tar.gz: Download the latest CMake source tarball, found at
    https://cmake.org/download/. Build it with:

        ./bootstrap --prefix=$PWD/cmake-linux64 && make && make install
        tar -czf cmake-linux64.tar.gz cmake-linux64/

cmake-mac.tar.gz: Follow the same instructions as above on a Mac, but replace
    cmake-linux64 with cmake-mac.

cmake-win32.zip: Update to the latest prebuilt release of CMake, found at
    https://cmake.org/download/. Use the file labeled "Windows ZIP". The
    download will be named cmake-VERSION-win32-x86.zip.

perl-win32.zip: Update to the latest 32-bit prebuilt "PortableZip" edition of
    Strawberry Perl, found at http://strawberryperl.com/releases.html. The
    download will be named strawberry-perl-VERSION-32bit-portable.zip.

yasm-win32.exe: Update to the appropriate release of Yasm. Use the same version
    as Chromium, found at
    https://chromium.googlesource.com/chromium/src/+/master/third_party/yasm/README.chromium
    Use the release at http://yasm.tortall.net/Download.html labeled
    "Win32 .exe". The download will be named yasm-VERSION-win32.exe.