Examine source code of LET'S FISH HTML5

{
  "manifest_version": 2,
  "name": "LETS FISH HTML5",
  "version": "20.0",
  "description": "With Let's Fish HTML5 Extension you can catch each fish in less than 2 seconds, without risk of banishment.",
  "icons": {
    "48": "icons/icone.png"
  },
  "permissions": [
    "tabs",
    "webRequest",
    "webRequestBlocking",
    "<all_urls>"
  ],
  "browser_action": {
    "default_icon": "icons/icone.png",
    "default_title": "TSG"
  },
  "web_accessible_resources": [
    "popup/options.html"
  ],
  "content_scripts": [
    {
      "all_frames": true,
      "matches": [
        "https://fish-fb.apps.tensquaregames.com/*",
        "*://*.apps.tensquaregames.com/*",
        "*://*.lets-fish.com/*",
        "*://apps.facebook.com/*",
        "*://fish.gamexpconnect.com/*"
      ],
      "js": [
        "content_script.js"
      ]
    }
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{483e1c4a-1656-442e-a4b5-9ced69ad05c3}"
    }
  }
}