Examine source code of Vim Compose

{
  "manifest_version": 3,
  "name": "Vim Compose",
  "description": "Compose mail and other text on the web as markdown in vim.",
  "version": "0.0.3",
  "browser_specific_settings": {
    "gecko": {
      "id": "{a2114633-87c6-47b8-871d-964df3c854df}"
    }
  },
  "icons": {
    "16": "icon16.png",
    "32": "icon32.png",
    "48": "icon48.png",
    "128": "icon128.png"
  },
  "action": {},
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "commands": {
    "_execute_action": {
      "suggested_key": {
        "default": "Ctrl+Space"
      },
      "description": "Edit in vim"
    }
  },
  "permissions": [
    "nativeMessaging",
    "activeTab",
    "scripting"
  ]
}