Examine source code of YouTube Speed Controller

{
  "manifest_version": 2,
  "name": "YouTube Speed Controller",
  "version": "1.0",
  "description": "Use YouTube's video speed control on any website.",
  "permissions": [
    "activeTab",
    "tabs",
    "storage",
    "browserAction",
    "background"
  ],
  "icons": {
    "48": "assets/speed-control48.png",
    "96": "assets/speed-control96.png",
    "128": "assets/speed-control128.png"
  },
  "content_scripts": [
    {
      "all_frames": true,
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "src/content_script.js"
      ]
    }
  ],
  "background": {
    "scripts": [
      "src/background.js"
    ],
    "persistent": false
  },
  "browser_action": {
    "default_popup": "src/popup/popup.html"
  },
  "options_ui": {
    "page": "src/options/options.html"
  },
  "commands": {
    "speed-down": {
      "suggested_key": {
        "default": "Ctrl+Shift+Comma"
      },
      "description": "Decrease playback speed"
    },
    "speed-up": {
      "suggested_key": {
        "default": "Ctrl+Shift+Period"
      },
      "description": "Increase playback speed"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{1f5b4ef9-d147-445d-911c-f4960d152c81}"
    }
  }
}