Examine source code of Playback speed

{
  "applications": {
    "gecko": {
      "id": "playbackSpeed@waldemar.b",
      "strict_min_version": "60.0a1"
    }
  },
  "permissions": [
    "tabs",
    "activeTab",
    "storage",
    "<all_urls>"
  ],
  "browser_action": {
    "default_icon": "icons/icon.svg",
    "theme_icons": [
      {
        "light": "icons/icon_light.svg",
        "dark": "icons/icon.svg",
        "size": 19
      }
    ],
    "default_title": "__MSG_extensionName__",
    "default_popup": "popup.html"
  },
  "description": "__MSG_extensionDescription__",
  "manifest_version": 2,
  "name": "__MSG_extensionName__",
  "default_locale": "en",
  "version": "1.4.4",
  "icons": {
    "48": "icons/icon.svg"
  },
  "background": {
    "scripts": [
      "bg.js"
    ]
  },
  "options_ui": {
    "page": "options.html",
    "browser_style": false
  },
  "commands": {
    "_execute_browser_action": {
      "description": "__MSG_openPopup__"
    },
    "ratePlus": {
      "suggested_key": {
        "default": "Alt+Shift+Right"
      },
      "description": "__MSG_increaseSpeed__"
    },
    "rateMinus": {
      "suggested_key": {
        "default": "Alt+Shift+Left"
      },
      "description": "__MSG_decreaseSpeed__"
    },
    "rateDefault": {
      "suggested_key": {
        "default": "Alt+Shift+Up"
      },
      "description": "__MSG_resetSpeed__"
    },
    "rewind": {
      "description": "__MSG_rewind__"
    },
    "fastforward": {
      "description": "__MSG_fastforward__"
    },
    "playpause": {
      "description": "__MSG_playPause__"
    },
    "loop": {
      "description": "__MSG_loop__"
    },
    "mute": {
      "description": "__MSG_mute__"
    }
  }
}