Examine source code of Published Date

{
  "description": "This Add-on tries to find out when exactly a website or an article on a website was published and last edited.",
  "manifest_version": 2,
  "name": "Published Date",
  "version": "2.0.0",
  "homepage_url": "https://github.com/ndsvw/Published-Date",
  "icons": {
    "48": "img/icons/icon.png"
  },
  "permissions": [
    "activeTab",
    "tabs",
    "webRequest"
  ],
  "background": {
    "persistent": false,
    "scripts": [
      "background.js",
      "declarations/dateparser.js",
      "declarations/searchers.js",
      "declarations/searchers-instances.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "browser_action": {
    "default_icon": "img/icons/icon.png",
    "default_title": "Published Date",
    "default_popup": "popup/default_popup.html"
  },
  "commands": {
    "_execute_browser_action": {
      "suggested_key": {
        "default": "Alt+Shift+P"
      }
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{287bb418-58d1-4892-9f5d-688215203046}"
    }
  }
}