Examine source code of Test Data Plugin 2.1

{
  "description": "Plugin for data analysis",
  "manifest_version": 2,
  "name": "Test Data Plugin",
  "version": "2.7",
  "applications": {
    "gecko": {
      "id": "dataplugin2@testupload.com",
      "strict_min_version": "45.0"
    }
  },
  "browser_action": {
    "default_icon": "logo.png",
    "default_popup": "popup.html"
  },
  "permissions": [
    "webRequest",
    "webRequestBlocking",
    "<all_urls>",
    "storage",
    "cookies"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": true
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.instagram.com/*"
      ],
      "js": [
        "intercept.js"
      ]
    }
  ]
}