Examine source code of LowCut Audio Toggle

{
  "manifest_version": 2,
  "name": "LowCut Audio Toggle",
  "version": "0.1",
  "description": "Toolbar toggle that applies a 330 Hz low-cut filter to page media.",
  "author": "Andreas Michael Fleckl",
  "homepage_url": "https://bubuit.net",
  "permissions": [
    "tabs",
    "storage",
    "activeTab"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "browser_action": {
    "default_title": "LowCut: OFF",
    "default_icon": {
      "16": "icons/icon-off-16.png",
      "32": "icons/icon-off-32.png",
      "48": "icons/icon-off-48.png"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content/content.js"
      ],
      "run_at": "document_start",
      "all_frames": true
    }
  ],
  "icons": {
    "48": "icons/icon-off-48.png",
    "128": "icons/icon-off-128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{4f0fb516-b3da-40ca-8a71-64cfcbcd06be}"
    }
  }
}