Examine source code of gfyclean

{
  "manifest_version": 2,
  "name": "gfyclean",
  "version": "2.4",
  "homepage_url": "https://github.com/Twinov/gfyclean",
  "description": "Cleans up gfycat, removing everything but the gif itself when a gfycat page is viewed.",
  "applications": {
    "gecko": {
      "id": "gfyclean@cock.email"
    }
  },
  "icons": {
    "16": "icons/gfyclean16.png",
    "32": "icons/gfyclean32.png",
    "48": "icons/gfyclean48.png",
    "96": "icons/gfyclean96.png",
    "128": "icons/gfyclean128.png"
  },
  "options_ui": {
    "page": "options.html",
    "browser_style": true,
    "open_in_tab": false
  },
  "permissions": [
    "*://*.gfycat.com/*",
    "*://*.imgur.com/*",
    "storage"
  ],
  "content_scripts": [
    {
      "matches": [
        "*://*.gfycat.com/*"
      ],
      "css": [
        "hideAll.css"
      ],
      "run_at": "document_start"
    },
    {
      "matches": [
        "*://*.gfycat.com/*"
      ],
      "js": [
        "removeGfy.js"
      ],
      "css": [
        "centerVid.css"
      ],
      "run_at": "document_end"
    },
    {
      "matches": [
        "*://*.imgur.com/*"
      ],
      "css": [
        "hideAll.css"
      ],
      "run_at": "document_start"
    },
    {
      "matches": [
        "*://*.imgur.com/*"
      ],
      "js": [
        "removeImgur.js"
      ],
      "css": [
        "centerVid.css"
      ],
      "run_at": "document_end"
    }
  ]
}