Examine source code of Page-Base64-Decoder

{
  "manifest_version": 2,
  "name": "Base64 Decoder",
  "description": "This extension decodes Base64-encoded strings on right-click.",
  "version": "1.2",
  "permissions": [
    "activeTab",
    "contextMenus",
    "tabs"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_end"
    }
  ],
  "browser_action": {
    "default_icon": {
      "16": "images/icon16.png",
      "32": "images/icon32.png",
      "48": "images/icon48.png",
      "128": "images/icon128.png"
    }
  },
  "icons": {
    "16": "images/icon16.png",
    "32": "images/icon32.png",
    "48": "images/icon48.png",
    "128": "images/icon128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{e43d5142-8487-417c-8c6e-15387835cf7e}"
    }
  }
}