Examine source code of MonoBass

{
  "manifest_version": 2,
  "name": "MonoBass",
  "description": "The plugin applies reduction of stereo signal by making low frequencies mono.",
  "version": "0.1.2",
  "author": "no9org@gmail.com",
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "http://*/*",
        "https://*/*",
        "file:///*/*"
      ],
      "js": [
        "monobass.js"
      ],
      "run_at": "document_idle"
    }
  ],
  "permissions": [
    "activeTab",
    "http://*/*",
    "https://*/*",
    "file:///*/*"
  ],
  "browser_action": {
    "default_icon": "icon19.png"
  },
  "icons": {
    "16": "icon16.png",
    "32": "icon32.png",
    "48": "icon48.png"
  },
  "applications": {
    "gecko": {
      "id": "{2d34c8eb-3be3-46de-9a8a-3e99e95feeb4}",
      "strict_min_version": "42.0"
    }
  }
}