Examine source code of Seeker

{
  "manifest_version": 2,
  "name": "Seeker",
  "description": "Quickly search and navigate through tabs, bookmarks, history, and more.",
  "version": "0.3.1",
  "icons": {
    "16": "icons/16.png",
    "32": "icons/32.png",
    "48": "icons/48.png",
    "128": "icons/128.png"
  },
  "permissions": [
    "tabs",
    "activeTab",
    "storage"
  ],
  "optional_permissions": [
    "bookmarks",
    "history"
  ],
  "commands": {
    "toggleMainDialog": {
      "suggested_key": {
        "default": "Alt+K"
      },
      "description": "Toggle the main dialog"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "seeker@seekerdev",
      "strict_min_version": "128.0"
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_title": "Seeker",
    "default_popup": "popup.html"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content-scripts/main.js"
      ]
    }
  ],
  "web_accessible_resources": [
    "content-scripts/main.css"
  ]
}