android google drive sdk和dropbox sdk

I'm working on file manager application for android. I use dropbox and google drive sdk. I want to implement some kind of Factory of cloud storage. eg if user selects google drive I'd create GoogleDriveClient whic inplements MyClient interface and use it. if user selects DropBox I'd create DropBoxClient which implements MyClient interface and use it. But there is a problem that I need activity in this client, because of sdk.. please provide your thoughts how can i make some abstraction of my cloud clients. Thank you.I'm working on file manager application for and