Examine source code of Element Blocker

{
  "manifest_version": 2,
  "name": "Element Blocker",
  "version": "2.2",
  "description": "Block popups, banners, chat widgets, notification bars, and more from appearing on any website.",
  "applications": {
    "gecko": {
      "id": "element-blocker@lukepeters.me"
    }
  },
  "icons": {
    "32": "icons/32.png",
    "48": "icons/48.png",
    "64": "icons/64.png",
    "96": "icons/96.png",
    "128": "icons/128.png"
  },
  "permissions": [
    "storage",
    "tabs"
  ],
  "browser_action": {
    "default_icon": "icons/32.png",
    "default_title": "Element Blocker",
    "default_popup": "popup/settings.html"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "element-blocker.js"
      ],
      "css": [
        "css/element-blocker.css"
      ],
      "run_at": "document_end"
    }
  ],
  "commands": {
    "toggleElementSelectorMode": {
      "suggested_key": {
        "default": "Ctrl+Alt+B",
        "mac": "Command+Alt+B"
      },
      "description": "Toggle element selector mode"
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  }
}