Examine source code of Share in

{
  "manifest_version": 2,
  "name": "Share in",
  "version": "2",
  "description": "Share links to Telegram or VK with one click!",
  "icons": {
    "48": "icons/icon48.png",
    "96": "icons/icon96.png"
  },
  "permissions": [
    "activeTab",
    "contextMenus"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_icon": "icons/icon96.png",
    "default_popup": "popup/popup.html",
    "default_title": "Share in..."
  },
  "options_ui": {
    "page": "options.html",
    "browser_style": true
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{b7ffc7d4-f309-49cc-b297-90e54d02c01c}"
    }
  }
}