Examine source code of Image Caption Extractor

{
  "manifest_version": 2,
  "name": "Image Caption Extractor",
  "version": "1.5.1",
  "description": "Extracts and displays captions or alt text from images across the internet",
  "permissions": [
    "<all_urls>",
    "storage",
    "tabs"
  ],
  "browser_action": {
    "default_icon": {
      "16": "src/assets/get_started16.png",
      "32": "src/assets/get_started32.png",
      "48": "src/assets/get_started48.png",
      "128": "src/assets/get_started128.png"
    },
    "default_popup": "popup.html"
  },
  "background": {
    "scripts": [
      "src/js/modules/background.js"
    ],
    "persistent": false
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "src/js/bundle/bundleContentScript.min.js"
      ]
    }
  ],
  "commands": {
    "toggle-feature": {
      "suggested_key": {
        "default": "Ctrl+Shift+Y",
        "linux": "Ctrl+Shift+U"
      }
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{a78dd517-b1a4-4495-8cde-29ae5d3bc5fd}"
    }
  }
}