Examine source code of StopImg

{
  "description": "Stop loading images by default",
  "manifest_version": 2,
  "name": "StopImg",
  "version": "0.5resigned1",
  "icons": {
    "16": "icons/icon_16.png",
    "32": "icons/icon_32.png",
    "48": "icons/icon_48.png",
    "96": "icons/icon_96.png",
    "128": "icons/icon_128.png"
  },
  "applications": {
    "gecko": {
      "id": "stopimg@mozilla.org",
      "strict_min_version": "48.0"
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "css": [
        "content.css"
      ],
      "all_frames": false
    }
  ],
  "options_ui": {
    "page": "options.html"
  },
  "browser_action": {
    "default_icon": "icons/icon_off.png",
    "default_title": "Turn images On",
    "browser_style": true
  },
  "permissions": [
    "storage",
    "contextMenus",
    "webRequest",
    "webRequestBlocking",
    "<all_urls>"
  ]
}