Also Send To Slack Channel Checker

manifest.json

{
  "update_url": "https://clients2.google.com/service/update2/crx",
  "name": "Also Send To Slack Channel Checker",
  "version": "1.0.3",
  "manifest_version": 2,
  "description": "Defaults Slack's 'also send to channel' thread option to checked",
  "homepage_url": "https://github.com/adam-p/slack-thread-to-channel-checker",
  "icons": {
    "128": "icons/icon128.png"
  },
  "permissions": [],
  "content_scripts": [
    {
      "matches": [
        "https://app.slack.com/client/*"
      ],
      "js": [
        "js/content.js"
      ]
    }
  ]
}