Downloading Node and NPM deps via gclient sync.

third_party/node/update_node_binaries

+#!/bin/bash
+
+# Copyright 2017 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.
+
+# Script for updating Node binaries.
+# 1) Update NODE_VERSION variable below to the desired version.
+# 2) Run this script.
+# 3) Upload the binaries to the Google Storage bucket (commands to upload
+#    binaries are printed at step 2, look for "gsutil.py").
+# 4) Land a CL with the changes generated by this script.
+
+set -eu
+cd "$(dirname "$0")"
+
+BASE_URL="https://nodejs.org/dist"
+NODE_VERSION="v6.9.4"
+
+update_unix() {
+  local SUFFIX="$1"
+  local FOLDER="$2"
+  local FILENAME="node-${NODE_VERSION}-${SUFFIX}.tar.gz"
+  local URL="${BASE_URL}/${NODE_VERSION}/${FILENAME}"
+
+  rm -f "${FOLDER}/${FILENAME}"
+  wget -P "${FOLDER}/" "${URL}"
+
+  # Check SHASUMS256 of downloaded binary.
+  local sha256_expected
+  sha256_expected="$(cat SHASUMS256.txt | grep ${FILENAME} | cut -d ' ' -f1)"

[palmer, 2017/01/13 20:56:27]

You can shorten this to

    sha256_expected="$(grep ${FILENAME} SHASUMS256.txt | cut -d ' ' -f1)"

I think it might be best to quote the file name, too; and the curly braces are
unnecessary here:

    sha256_expected="$(grep "$FILENAME" SHASUMS256.txt | cut -d ' ' -f1)"

[dpapad, 2017/01/13 22:35:15]

Done.

+  local sha256_actual

[palmer, 2017/01/13 20:56:27]

Nit: FWIW, you can combine the declaration and the definition:

    local sha256_actual=...

[dpapad, 2017/01/13 22:35:15]

I am following the styleguide, which says:
"Declare function-specific variables with local. Declaration and assignment
should be on different lines."

See,
https://google.github.io/styleguide/shell.xml?showone=Use_Local_Variables#Use....

+  sha256_actual="$(sha256sum ${FOLDER}/${FILENAME} | cut -d ' ' -f1)"

[palmer, 2017/01/13 20:56:28]

Quotes here too, I think.

[dpapad, 2017/01/13 22:35:15]

Done.

+
+  if [ "${sha256_expected}" != "${sha256_actual}" ]; then
+    echo "SHA256 mismatch. Exiting..."
+    exit 1
+  fi
+
+  # Unpack temporarily, delete NPM symlink and re-pack.
+  tar xfz "${FOLDER}/${FILENAME}" -C "${FOLDER}/"
+  rm "${FOLDER}/${FILENAME}"
+  rm "${FOLDER}/node-${NODE_VERSION}-${SUFFIX}/bin/npm"
+
+  # Drop the version info from the name, since it is redundant and would make
+  # rolling new versions more involved.
+  rm -rf "${FOLDER}/node-${SUFFIX}/"
+  mv "${FOLDER}/node-${NODE_VERSION}-${SUFFIX}/" "${FOLDER}/node-${SUFFIX}/"
+  tar cfz "${FOLDER}/node-${SUFFIX}.tar.gz" -C "${FOLDER}" "node-${SUFFIX}/"
+  local sha1
+  sha1="$(sha1sum ${FOLDER}/node-${SUFFIX}.tar.gz | cut -d ' ' -f1)"
+  echo "${sha1}" > "${FOLDER}/node-${SUFFIX}.tar.gz.sha1"
+  echo "Please execute manually the following:"
+  echo "> gsutil.py cp ${FOLDER}/node-${SUFFIX}.tar.gz gs://chromium-nodejs/${NODE_VERSION:1}/${sha1}"
+  echo "DONE updating for ${SUFFIX}."
+}
+
+update_win() {
+  local FILENAME="node.exe"
+  local FOLDER="win"
+  local WINDOWS_URL="${BASE_URL}/${NODE_VERSION}/win-x64/${FILENAME}"
+  rm -f "${FOLDER}/${FILENAME}"
+  wget -P "${FOLDER}/" "${WINDOWS_URL}"
+
+  # Check SHASUMS256 of downloaded binary.
+  local sha256_expected
+  sha256_expected="$(cat SHASUMS256.txt | grep win-x64/${FILENAME} | cut -d ' ' -f1)"
+  local sha256_actual
+  sha256_actual="$(sha256sum ${FOLDER}/${FILENAME} | cut -d ' ' -f1)"
+
+  if [ "${sha256_expected}" != "${sha256_actual}" ]; then
+    echo "SHA256 mismatch. Exiting..."
+    exit 1
+  fi
+
+  local sha1
+  sha1="$(sha1sum ${FOLDER}/node.exe | cut -d ' ' -f1)"
+  echo "${sha1}" > "${FOLDER}/node.exe.sha1"
+  echo "Please execute manually the following:"
+  echo "> gsutil.py cp ${FOLDER}/node.exe gs://chromium-nodejs/${NODE_VERSION:1}/${sha1}"
+  echo "DONE updating Windows."
+}
+
+# First download checksum file.
+rm "SHASUMS256.txt"
+wget "https://nodejs.org/dist/latest-v6.x/SHASUMS256.txt"
+
+update_unix "darwin-x64" "mac"
+update_unix "linux-x64" "linux"
+update_win
+
+# Update DEPS to point to the new Google Storage bucket subfolder.
+sed -i "s@\(chromium-nodejs/\)\([0-9\.]\)\+@\1${NODE_VERSION:1}@" ../../DEPS