Add ".install.sh" script and copy it to the build folder.

Bug: 1031552
Change-Id: I065956f2eb6cde4354fcff23d03912836b4a14c9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1993142Reviewed-by: Sorin Jianu <sorin@chromium.org>
Reviewed-by: Joshua Pawlicki <waffles@chromium.org>
Commit-Queue: Mila Green <milagreen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#729975}

chrome/updater/mac/BUILD.gn

@@ -7,6 +7,7 @@ import("//build/config/mac/rules.gni")
 group("mac") {
   deps = [
     ":updater_bundle",
+    ":updater_install_script",
     ":updater_setup",
   ]
 }
@@ -87,3 +88,12 @@ executable("updater_setup") {
     ":updater_setup_sources",
   ]
 }
+
+copy("updater_install_script") {
+  sources = [
+    "setup/.install.sh",
+  ]
+  outputs = [
+    "$root_build_dir/chrome/updater/.install.sh",
+  ]
+}

chrome/updater/mac/setup/.install.sh

+#!/bin/sh
+# Copyright 2020 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.
+
+# This script invokes updater_setup
+
+SCRIPT_PATH="$(dirname "$0")"
+
+"$SCRIPT_PATH/updater_setup"