Examine source code of Scroller++ by DrMusti

{
  "manifest_version": 2,
  "name": "Scroller++ by DrMusti",
  "version": "1.0.2",
  "description": "Scroller button....",
  "icons": {
    "16": "assets/aaa16.png",
    "24": "assets/aaa24.png",
    "32": "assets/aaa32.png"
  },
  "permissions": [
    "tabs",
    "activeTab",
    "<all_urls>"
  ],
  "browser_action": {
    "default_icon": {
      "16": "assets/mouse16.png",
      "24": "assets/mouse24.png",
      "32": "assets/mouse32.png"
    },
    "default_title": "Scroller."
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "src/toggle-css.js"
      ]
    }
  ],
  "background": {
    "scripts": [
      "src/background.js"
    ]
  }
}