Examine source code of PassMass

{
  "name": "PassMass",
  "author": "Sepehr Aryani",
  "manifest_version": 2,
  "homepage_url": "https://github.com/sepisoad/passmass",
  "version": "0.1",
  "description": "storage less password manager",
  "permissions": ["<all_urls>", "clipboard", "activeTab", "declarativeContent", "storage"],  
  "background": {
    "scripts": ["background.js"],
    "persistent": false
  },
  // "options_page": "options.html",
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "16": "images/passmass_16.png",
      "24": "images/passmass_24.png",
      "32": "images/passmass_32.png",
      "64": "images/passmass_64.png",
      "128": "images/passmass_128.png"
    }
  },  
  "icons": {
    "16": "images/passmass_16.png",
    "24": "images/passmass_24.png",
    "32": "images/passmass_32.png",
    "64": "images/passmass_64.png",
    "128": "images/passmass_128.png"
  },
  // firefox
  "applications": {
    "gecko": {
      "id": "sepehr.aryani@gmail.com",
      "strict_min_version": "53.0"
    }
  }
}