Examine source code of SEOZoomBar

{
  "background": {
    "scripts": [
      "eventPage.js"
    ],
    "css": [
      "c-page.css"
    ]
  },
  "browser_action": {
    "default_icon": "i-icon16.png",
    "default_popup": "popup.html"
  },
  "content_scripts": [
    {
      "css": [
        "c-seozoom.css"
      ],
      "js": [
        "jquery-3.3.1.min.js",
        "base.js",
        "popup.js"
      ],
      "matches": [
        "http://*/*",
        "https://*/*"
      ]
    },
    {
      "css": [
        "c-toolbar.css"
      ],
      "exclude_matches": [
        "*://*.google.com/*",
        "*://*.google.it/*",
        "*://*.facebook.com/*",
        "*://*.facebook.com/*",
        "*://*.facebook.it/*",
        "*://*.youtube.it/*",
        "*://*.youtube.com/*",
        "*://*.twitter.it/*",
        "*://*.twitter.com/*",
        "*://*.linkedin.it/*",
        "*://*.linkedin.com/*",
        "*://*.suite.seozoom.it/*"
      ],
      "js": [
        "toolbar.js",
        "translations.js"
      ],
      "matches": [
        "http://*/*",
        "https://*/*"
      ]
    }
  ],
  "description": "A SEOZoom extension!",
  "icons": {
    "16": "i-icon16.png",
    "48": "i-icon48.png",
    "128": "i-icon128.png"
  },
  "manifest_version": 2,
  "name": "SEOZoomBar",
  "permissions": [
    "https://*/",
    "http://*/",
    "tabs",
    "storage",
    "contextMenus"
  ],
  "short_name": "SEOZoomBar",
  "update_url": "https://clients2.google.com/service/update2/crx",
  "version": "2.0.3",
  "web_accessible_resources": [
    "toolbar.html",
    "c-toolbar.css",
    "base.js",
    "helper.js",
    "toolbar.js",
    "seozoom.js",
    "translations.js",
    "c-seozoom.css",
    "c-page.css",
    "i-lens.png",
    "i-close.png",
    "i-info.png",
    "i-logo-toolbar.png",
    "i-icon48.png",
    "i-max.png",
    "i-data.png",
    "i-analysis.png",
    "i-down.png",
    "i-it.png",
    "i-en.png",
    "world.svg",
    "screen.svg"
  ]
}