Examine source code of IdleStudy

{
  "manifest_version": 2,
  "name": "IdleStudy",
  "description": "Learn while idle",
  "version": "0.1.7",
  "icons": {
    "48": "icon-48.a314d5f4.png",
    "96": "icon-96.df0ac913.png"
  },
  "browser_action": {
    "default_icon": "icon-96.df0ac913.png",
    "default_popup": "popup.147200f6.html"
  },
  "permissions": [
    "tabs",
    "storage",
    "identity"
  ],
  "web_accessible_resources": [
    "flashcard/flashcard.html"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "extension@idlestudy.com"
    }
  },
  "background": {
    "scripts": [
      "browser-polyfill.b9dfef5b.js",
      "background.7bb8b3ca.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "browser-polyfill.b9dfef5b.js",
        "content-script.97b7531f.js"
      ],
      "css": []
    }
  ]
}