Examine source code of Toggle Save-Data Header

{
  "author": "igorlogius",
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "theme_icons": [
      {
        "light": "dark-256.png",
        "dark": "light-256.png",
        "size": 256
      },
      {
        "light": "dark-128.png",
        "dark": "light-128.png",
        "size": 128
      },
      {
        "light": "dark-64.png",
        "dark": "light-64.png",
        "size": 64
      },
      {
        "light": "dark-32.png",
        "dark": "light-32.png",
        "size": 32
      },
      {
        "light": "dark-16.png",
        "dark": "light-16.png",
        "size": 16
      }
    ]
  },
  "commands": {
    "copy-action": {
      "suggested_key": {
        "default": "Alt+Shift+M"
      }
    }
  },
  "icons": {
    "256": "light-256.png"
  },
  "manifest_version": 2,
  "name": "Toggle Save-Data Header",
  "permissions": [
    "<all_urls>",
    "webRequest",
    "webRequestBlocking",
    "storage"
  ],
  "version": "1.1.1",
  "browser_specific_settings": {
    "gecko": {
      "id": "{f4daa597-fc41-4a5b-869f-66bf1cf909b4}"
    }
  }
}