Examine source code of SoundCloud Control

{
  "manifest_version": 2,
  "name": "SoundCloud Control",
  "version": "0.7.0",
  "description": "Control SoundCloud player controls without switching tabs",
  "homepage_url": "https://github.com/johannesfischer/soundcloud-control/",
  "author": "Johannes Fischer",
  "applications": {
    "gecko": {
      "id": "{ecd8bf54-1dea-4415-9b5e-c9452d1255fe}",
      "strict_min_version": "74.0"
    }
  },
  "icons": {
    "128": "soundcloud_dark_128.png"
  },
  "permissions": [
    "https://soundcloud.com/*",
    "storage",
    "tabs"
  ],
  "browser_action": {
    "browser_style": true,
    "default_icon": {
      "128": "soundcloud_dark_128.png"
    },
    "theme_icons": [
      {
        "light": "soundcloud_light_128.png",
        "dark": "soundcloud_dark_128.png",
        "size": 128
      }
    ],
    "default_popup": "popup/popup.html"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.soundcloud.com/*"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_end"
    }
  ],
  "commands": {
    "toggle-playback": {
      "suggested_key": {
        "default": "Ctrl+Shift+6"
      },
      "description": "Toggle SoundCloud playback"
    },
    "previous-song": {
      "suggested_key": {
        "default": "Ctrl+Shift+5"
      },
      "description": "Rewind song playing on SoundCloud"
    },
    "next-song": {
      "suggested_key": {
        "default": "Ctrl+Shift+7"
      },
      "description": "Skip to next song on SoundCloud"
    }
  }
}