Examine source code of Captions Extractor

{
  "manifest_version": 2,
  "name": "Captions Extractor",
  "version": "0.0.1",
  "description": "Extract caption text of vedio if it is a .srt file",
  "icons": {
    "48": "icons/travel.png"
  },
  "browser_action": {
    "default_icon": "icons/travel.png",
    "default_title": "Captions Extractor",
    "default_popup": "popup/popup.html"
  },
  "permissions": [
    "devtools"
  ],
  "devtools_page": "devtools/devtool.html"
}