Examine source code of Playback Speed Control

{
  "manifest_version": 2,
  "name": "Playback Speed Control",
  "description": "A playback speed controller for video and audio players",
  "version": "1.0.32",
  "icons": {
    "16": "icons/16.png",
    "32": "icons/32.png",
    "48": "icons/48.png",
    "128": "icons/128.png"
  },
  "permissions": [
    "storage"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "playback-speed-controller@dougg0k",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_title": "Playback Speed Control",
    "default_popup": "popup.html"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "all_frames": true,
      "run_at": "document_end",
      "js": [
        "content-scripts/content.js"
      ]
    }
  ]
}