Examine source code of Previous Page Button

{
  "manifest_version": 2,
  "default_locale": "en",
  "browser_specific_settings": {
    "gecko": {
      "id": "Prev_Page_Button@firefox.clu-os.net",
      "strict_min_version": "58.0"
    }
  },
  "name": "__MSG_extensionName__",
  "description": "__MSG_extensionDescription__",
  "version": "0.1.1",
  "icons": {
    "48": "_images/icon.svg",
    "96": "_images/icon.svg"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "browser_style": false,
    "default_title": "__MSG_defaultTitle__",
    "default_icon": "_images/action.dark.svg",
    "theme_icons": [
      {
        "dark": "_images/action.dark.svg",
        "light": "_images/action.light.svg",
        "size": 16
      },
      {
        "dark": "_images/action.dark.svg",
        "light": "_images/action.light.svg",
        "size": 32
      }
    ]
  },
  "permissions": [
    "management"
  ]
}