Examine source code of Slack Hebrew

{
  "manifest_version": 2,
  "name": "Slack Hebrew",
  "version": "1.5",
  "description": "In Slack web app: modify direction to rtl, but only for messages containing hebrew characters",
  "icons": {
    "128": "icon.png"
  },
  "author": "Shlomi Matichin <shlomomatichin@gmail.com>",
  "page_action": {
    "default_title": "Slack Hebrew"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.slack.com/*"
      ],
      "js": [
        "slack-hebrew.js"
      ],
      "all_frames": true
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{1a16a9b9-d269-43cd-a8ed-572b3fab27bf}"
    }
  }
}