Examine source code of Translate Comments

{
  "manifest_version": 2,
  "name": "Translate Comments",
  "version": "1.0",
  "description": "Translate comments on YouTube, Facebook, etc.",
  "permissions": [
    "activeTab",
    "https://translate.googleapis.com/"
  ],
  "content_scripts": [
    {
      "matches": [
        "*://*.youtube.com/*",
        "*://*.facebook.com/*"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "browser_action": {
    "default_icon": "icon.png",
    "default_title": "Translate Comments"
  },
  "icons": {
    "48": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{ac385960-3995-4f8a-bf66-5ae740eb33b0}"
    }
  }
}