@ScottNett Your MainActivtiy looks correct. As for the WebChromeClient, you need to create a custom renderer for your webview where you have to create an instance of the subclassed WebChromeClient and set it with the SetWebChromeClient on the webview.
button rendered by element, browser opens a Dialog box where I can choose a file to upload. However, in the android 3.0 emulator / AVD, when I click on "Choose file", nothing happens, no file dialog is opened!!!