Examine source code of Player Extractor

{
  "manifest_version": 2,
  "name": "Player Extractor",
  "description": "Mozilla Firefox extension to extract video player to external popup window.",
  "version": "0.3resigned1",
  "icons": {
    "16": "images/tv-16.png",
    "24": "images/tv-24.png",
    "32": "images/tv-32.png",
    "64": "images/tv-64.png",
    "128": "images/tv-128.png"
  },
  "permissions": [
    "webNavigation"
  ],
  "browser_action": {
    "default_title": "Extract Player",
    "default_icon": {
      "16": "images/tv-16.png",
      "24": "images/tv-24.png",
      "32": "images/tv-32.png"
    }
  },
  "background": {
    "scripts": [
      "common.js",
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "js": [
        "jquery-3.0.0.min.js",
        "common.js",
        "content.js"
      ],
      "matches": [
        "<all_urls>"
      ],
      "run_at": "document_end",
      "all_frames": true
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{7575b305-9f88-456f-8fa1-4c4ae454e7bf}"
    }
  }
}