Examine source code of switch between pages

{
  "manifest_version": 2,
  "name": "Tab Manager Plus",
  "version": "1.0",
  "description": "View, search, and manage open tabs بسهولة.",
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_title": "Tab Manager Plus",
    "default_popup": "popup.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "sunnyboyj.o.s.eph.2.2@gmail.com",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "permissions": [
    "tabs"
  ]
}