Examine source code of Toggle checkboxes

{
  "name": "Toggle checkboxes",
  "description": "Productivity tool to toggle all checkboxes (only non-disabled & readable once) on any page.",
  "version": "1.1",
  "manifest_version": 2,
  "browser_action": {
    "default_title": "Click to toggle all checkboxes",
    "default_icon": {
      "16": "./icons/16.png",
      "32": "./icons/32.png",
      "48": "./icons/48.png",
      "128": "./icons/128.png"
    }
  },
  "permissions": [
    "activeTab",
    "contextMenus",
    "http://*/*",
    "https://*/*"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "context.js"
      ],
      "all_frames": true
    }
  ],
  "icons": {
    "16": "./icons/16.png",
    "32": "./icons/32.png",
    "48": "./icons/48.png",
    "128": "./icons/128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{e8c86e54-b5de-4652-be9e-017ef8c65855}"
    }
  }
}