Examine source code of Quick Compose for Gmail

{
  "background": {
    "scripts": [
      "js/background.js"
    ]
  },
  "browser_action": {
    "default_icon": "static/128.png",
    "default_title": "Compose New Email",
    "browser_style": false
  },
  "description": "Quickly open the compose window of Gmail. Keyboard Shortcut: Alt + C.",
  "homepage_url": "https://browsernative.com/gmail-firefox-extension/",
  "icons": {
    "128": "static/128.png"
  },
  "manifest_version": 2,
  "options_ui": {
    "page": "options.html",
    "open_in_tab": true
  },
  "name": "Quick Compose for Gmail",
  "version": "0.6.1",
  "permissions": [
    "contextMenus",
    "tabs"
  ],
  "commands": {
    "_execute_browser_action": {
      "suggested_key": {
        "default": "Alt+C"
      },
      "description": "Compose new email"
    }
  }
}