Examine source code of Subtitle Uploader

{
  "manifest_version": 2,
  "name": "Subtitle Uploader",
  "version": "1.0",
  "description": "Upload subtitles to a detected video element.",
  "homepage_url": "https://github.com/baun-baggi/subtitle-uploader",
  "icons": {
    "48": "icons/icon-48.png",
    "96": "icons/icon-96.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "subtitle-uploader@localhost.com",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "permissions": [
    "activeTab",
    "<all_urls>",
    "storage",
    "tabs"
  ],
  "browser_action": {
    "default_popup": "popup/popup.html",
    "default_icon": "icons/icon-32.png",
    "default_title": "Subtitle Uploader"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content_scripts/subtitles.js"
      ]
    }
  ]
}