Examine source code of Slick Write

{
  "manifest_version": 2,
  "name": "Slick Write",
  "version": "1.0.0.10resigned1",
  "description": "Analyze your writing with Slick Write.",
  "homepage_url": "https://www.slickwrite.com",
  "author": "RussTek LLC",
  "icons": {
    "128": "icons/icon-128.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "js": [
        "content.js"
      ],
      "matches": [
        "<all_urls>"
      ],
      "match_about_blank": true,
      "all_frames": true
    }
  ],
  "browser_action": {
    "default_icon": "icons/icon-128.png",
    "default_title": "Check your writing with Slick Write"
  },
  "permissions": [
    "https://www.slickwrite.com/poster",
    "activeTab",
    "contextMenus",
    "notifications",
    "tabs"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "firefox@slickwrite.com"
    }
  }
}