Examine source code of Volume Control

{
  "manifest_version": 2,
  "name": "Volume Control",
  "version": "2.0.2",
  "description": "A fix for loud volume.",
  "icons": {
    "48": "resources/icon1-48.png",
    "96": "resources/icon1-96.png"
  },
  "applications": {
    "gecko": {
      "id": "volumecontrol@my.manybuddies.com",
      "strict_min_version": "70.0"
    }
  },
  "browser_action": {
    "browser_style": true,
    "default_icon": {
      "48": "resources/icon2-48.png",
      "96": "resources/icon2-96.png"
    },
    "default_title": "Volume Control",
    "default_popup": "ui_panel/ui_panel.html"
  },
  "options_ui": {
    "page": "ui_options/ui_options.html",
    "browser_style": true,
    "open_in_tab": false
  },
  "background": {
    "scripts": [
      "bs_engine.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "cs_volume.control.js"
      ],
      "match_about_blank": true,
      "all_frames": true,
      "run_at": "document_start"
    }
  ],
  "permissions": [
    "<all_urls>",
    "storage",
    "unlimitedStorage",
    "tabs"
  ]
}