Examine source code of Tunable Image Block

{
  "name": "Tunable Image Block",
  "version": "1.7.2resigned1",
  "description": "Block images without breaking the page. Tune restriction of images by data size.",
  "manifest_version": 2,
  "permissions": [
    "<all_urls>",
    "tabs",
    "activeTab",
    "webRequest",
    "webRequestBlocking",
    "storage"
  ],
  "icons": {
    "16": "icon16.png",
    "48": "icon48.png",
    "128": "icon128.png"
  },
  "browser_action": {
    "default_title": "Tunable Image Block",
    "default_icon": "icon16.png",
    "default_popup": "popup.html"
  },
  "background": {
    "page": "background.html",
    "persistent": true
  },
  "content_scripts": [
    {
      "matches": [
        "http://*/*",
        "https://*/*"
      ],
      "js": [
        "js/api.js",
        "js/content.js"
      ],
      "css": [
        "css/image.css"
      ],
      "run_at": "document_start"
    }
  ],
  "options_ui": {
    "page": "options.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{0044daad-3ff6-422a-8a2b-8d8bb602ac5a}"
    }
  }
}