Add a snapshot of flutter/engine/src/build to our sdk

build/mac/make_more_helpers.sh

Index: build/mac/make_more_helpers.sh
diff --git a/build/mac/make_more_helpers.sh b/build/mac/make_more_helpers.sh
new file mode 100755
index 0000000000000000000000000000000000000000..6f5c4749ebf4dc7c0de8deff03e0c2d8ff7b2246
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+++ b/build/mac/make_more_helpers.sh
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+#!/bin/bash
+
+# Copyright (c) 2012 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.
+
+# Usage: make_more_helpers.sh <directory_within_contents> <app_name>
+#
+# This script creates additional helper .app bundles for Chromium, based on
+# the existing helper .app bundle, changing their Mach-O header's flags to
+# enable and disable various features. Based on Chromium Helper.app, it will
+# create Chromium Helper EH.app, which has the MH_NO_HEAP_EXECUTION bit
+# cleared to support Chromium child processes that require an executable heap,
+# and Chromium Helper NP.app, which has the MH_PIE bit cleared to support
+# Chromium child processes that cannot tolerate ASLR.
+#
+# This script expects to be called from the chrome_exe target as a postbuild,
+# and operates directly within the built-up browser app's versioned directory.
+#
+# Each helper is adjusted by giving it the proper bundle name, renaming the
+# executable, adjusting several Info.plist keys, and changing the executable's
+# Mach-O flags.
+
+set -eu
+
+make_helper() {
+  local containing_dir="${1}"
+  local app_name="${2}"
+  local feature="${3}"
+  local flags="${4}"
+
+  local helper_name="${app_name} Helper"
+  local helper_stem="${containing_dir}/${helper_name}"
+  local original_helper="${helper_stem}.app"
+  if [[ ! -d "${original_helper}" ]]; then
+    echo "${0}: error: ${original_helper} is a required directory" >& 2
+    exit 1
+  fi
+  local original_helper_exe="${original_helper}/Contents/MacOS/${helper_name}"
+  if [[ ! -f "${original_helper_exe}" ]]; then
+    echo "${0}: error: ${original_helper_exe} is a required file" >& 2
+    exit 1
+  fi
+
+  local feature_helper="${helper_stem} ${feature}.app"
+
+  rsync -acC --delete --include '*.so' "${original_helper}/" "${feature_helper}"
+
+  local helper_feature="${helper_name} ${feature}"
+  local helper_feature_exe="${feature_helper}/Contents/MacOS/${helper_feature}"
+  mv "${feature_helper}/Contents/MacOS/${helper_name}" "${helper_feature_exe}"
+
+  local change_flags="$(dirname "${0}")/change_mach_o_flags.py"
+  "${change_flags}" ${flags} "${helper_feature_exe}"
+
+  local feature_info="${feature_helper}/Contents/Info"
+  local feature_info_plist="${feature_info}.plist"
+
+  defaults write "${feature_info}" "CFBundleDisplayName" "${helper_feature}"
+  defaults write "${feature_info}" "CFBundleExecutable" "${helper_feature}"
+
+  cfbundleid="$(defaults read "${feature_info}" "CFBundleIdentifier")"
+  feature_cfbundleid="${cfbundleid}.${feature}"
+  defaults write "${feature_info}" "CFBundleIdentifier" "${feature_cfbundleid}"
+
+  cfbundlename="$(defaults read "${feature_info}" "CFBundleName")"
+  feature_cfbundlename="${cfbundlename} ${feature}"
+  defaults write "${feature_info}" "CFBundleName" "${feature_cfbundlename}"
+
+  # As usual, defaults might have put the plist into whatever format excites
+  # it, but Info.plists get converted back to the expected XML format.
+  plutil -convert xml1 "${feature_info_plist}"
+
+  # `defaults` also changes the file permissions, so make the file
+  # world-readable again.
+  chmod a+r "${feature_info_plist}"
+}
+
+if [[ ${#} -ne 2 ]]; then
+  echo "usage: ${0} <directory_within_contents> <app_name>" >& 2
+  exit 1
+fi
+
+DIRECTORY_WITHIN_CONTENTS="${1}"
+APP_NAME="${2}"
+
+CONTENTS_DIR="${BUILT_PRODUCTS_DIR}/${CONTENTS_FOLDER_PATH}"
+CONTAINING_DIR="${CONTENTS_DIR}/${DIRECTORY_WITHIN_CONTENTS}"
+
+make_helper "${CONTAINING_DIR}" "${APP_NAME}" "EH" "--executable-heap"
+make_helper "${CONTAINING_DIR}" "${APP_NAME}" "NP" "--no-pie"