Set up Chrome master_preferences file for Pre-installed Extensions. Cf. https://www.chromium.org/administrators/pre-installed-extensions/

pre-install-extension.py

#!/usr/bin/env python3

import sys
import os
import json

args = sys.argv[1:]

if not args:
    print(
        f"Usage: {sys.argv[0]} [-o <initial_preferences_file>] <Preferences_file> [<extension_id..>]")
    exit(1)

output_file = None

if args[0] == "-o":
    output_file = args[1]
    args = args[2:]

exts = json.load(open(args[0]))['extensions']["settings"]
out_settings = {}

if len(args) == 1:
    print("Please choose extension id(s):\n")
    for ext in exts:
        print(f"{ext}\t{exts[ext]['manifest']['name']}")
    exit(0)

for ext_id in args[1:]:
    ext = exts[ext_id]

    out_cfg = dict(
        location=1,
        path=os.path.join(os.path.split(ext["path"])[0], "0.0"),
        manifest=dict(
            version="0.0",
            name=ext["manifest"]["name"]+" (installing)",
            manifest_version=2
        )
    )

    for k in ("key", "update_url", "permissions", "content_scripts"):
        if k in ext["manifest"]:
            out_cfg["manifest"][k] = ext["manifest"][k]

    if "granted_permissions" in ext:
        out_cfg["granted_permissions"] = ext["granted_permissions"]
    out_settings[ext_id] = out_cfg

if not output_file:
    for ext_id in out_settings:
        p_id = "" if len(out_settings) == 1 else f"{ext_id}: "
        print(f"{p_id}{json.dumps(out_settings[ext_id])}")
    exit(0)

try:
    output_preferences = json.load(open(output_file))
except IOError:
    output_preferences = {}

for ext_id in out_settings:
    output_preferences.setdefault("extensions", {}).setdefault(
        "settings", {})[ext_id] = out_settings[ext_id]

json.dump(output_preferences, open(output_file, "w"))