Examine source code of Web Dev Helper

{
  "manifest_version": 2,
  "name": "__MSG_extensionName__",
  "version": "1.0",
  "description": "__MSG_extensionDescription__",
  "icons": {
    "48": "icons/icon.png"
  },
  "browser_action": {
    "default_icon": {
      "48": "icons/icon.png"
    },
    "default_title": "__MSG_extensionName__",
    "default_popup": "popup.html"
  },
  "permissions": [
    "activeTab"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{53c21f8c-58ec-430a-9bec-775cc380b811}"
    }
  }
}