iOS Extension Web Page Preprocessor

Prrprocessor.js

var MyPreprocessor = function() {};
MyPreprocessor.prototype = {
run: function(arguments) {
    // Pass the baseURI of the webpage to the extension.
    arguments.completionFunction({"URL": document.URL, "pageSource": document.documentElement.outerHTML, "title": document.title, "selection": window.getSelection().toString()});
}
};
// The JavaScript file must contain a global object named "ExtensionPreprocessingJS".
var ExtensionPreprocessingJS = new MyPreprocessor;

Is it a way to get the logo image source?