Examine source code of MarmuPass

{
  "manifest_version": 2,
  "name": "PasswordManager",
  "version": "1.3.1",
  "description": "Automatically injects passwords and usernames from https://password.marmulab.lol",
  "homepage_url": "https://password.marmulab.lol",
  "permissions": [
    "activeTab",
    "storage",
    "*://*/*",
    "tabs",
    "notifications"
  ],
  "web_accessible_resources": [
    "popup/username_selector.html"
  ],
  "browser_action": {
    "default_icon": "icons/icon32.png",
    "default_title": "Password Manager",
    "default_popup": "popup/settings.html"
  },
  "sidebar_action": {
    "default_icon": {
      "32": "icons/icon32.png"
    },
    "default_title": "Saved Passwords",
    "default_panel": "popup/username_selector.html",
    "open_at_install": true
  },
  "icons": {
    "32": "icons/icon32.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "commands": {
    "_execute_sidebar_action": {
      "suggested_key": {
        "default": "Alt+P"
      }
    }
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "inject.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{0c3a3cd7-5668-4304-9c8e-174c2111b2c1}"
    }
  }
}