Examine source code of Steam Bulk Sell

{
  "applications": {
    "gecko": {
      "strict_min_version": "62.0",
      "id": "{c7e15941-6082-499c-a52c-94015f7eb5d1}"
    }
  },
  "browser_action": {
    "browser_style": true,
    "default_icon": "./icons/extension.svg",
    "default_title": "Steam Bulk Sell",
    "default_popup": "popup.html"
  },
  "background": {
    "scripts": [
      "./background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "*://steamcommunity.com/id/*/inventory*",
        "*://steamcommunity.com/profiles/*/inventory*",
        "*://steamcommunity.com/market/sellitem/*"
      ],
      "js": [
        "./content.js"
      ],
      "css": [
        "./content.css"
      ],
      "run_at": "document_idle",
      "all_frames": true
    }
  ],
  "permissions": [
    "cookies",
    "contextualIdentities",
    "webRequest",
    "webRequestBlocking",
    "*://steamcommunity.com/id/*/inventory*",
    "*://steamcommunity.com/profiles/*/inventory*",
    "*://steamcommunity.com/market/sellitem/*"
  ],
  "icons": {
    "16": "./icons/16.png",
    "32": "./icons/32.png",
    "48": "./icons/48.png",
    "64": "./icons/64.png",
    "128": "./icons/128.png"
  },
  "description": "__MSG_extensionDescription__",
  "homepage_url": "https://github.com/k5md/Steam-Bulk-Sell-webextension",
  "manifest_version": 2,
  "name": "Steam Bulk Sell",
  "version": "1.2.2",
  "default_locale": "en"
}