Examine source code of Video Muter

{
  "name": "Muter",
  "version": "0.1",
  "description": "Mute html5 video with shortkey.",
  "permissions": [
    "storage",
    "tabs",
    "webRequest",
    "webRequestBlocking",
    "<all_urls>"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "page_action": {
    "default_popup": "popup.html"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_end"
    }
  ],
  "commands": {
    "pause": {
      "suggested_key": {
        "mac": "Command+Shift+Z"
      },
      "description": "Pause video"
    }
  },
  "manifest_version": 2
}