Examine source code of ParaReader

{
  "manifest_version": 2,
  "name": "ParaReader",
  "version": "0.3",
  "description": "Read selected text comfortably",
  "permissions": [
    "activeTab"
  ],
  "background": {
    "scripts": [
      "reader-bg.js"
    ]
  },
  "commands": {
    "toggle-feature": {
      "suggested_key": {
        "default": "Alt+Shift+X",
        "mac": "Ctrl+Shift+X"
      },
      "description": "Send a 'toggle-feature' event to the extension"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "tingle.js",
        "reader.js"
      ],
      "css": [
        "tingle.css",
        "reader.css"
      ]
    }
  ]
}