I dont understand why you're using requesturl for this.
PHP Code:
http://chart.apis.google.com/chart?chs=150x150&cht=qr&chld=L|0&chl=
Is an image.
So you could just simple do when the button is pressed, just have
PHP Code:
Generated_MultiLine.text = "<img src='http://chart.apis.google.com/chart?chs=150x150&cht=qr&chld=L|0&chl=" @ Generate_Encode.text @ "'>";