View PDF, DOC, XLS and PPT files without downloading them to your device. Save downloading time and space on your device. Here's how it works: Just before a compatible file starts to download, you are prompted to open the file in the Google Docs Viewer instead. If you choose to open in the online viewer, a new tab is opened and the viewer is loaded.
If you don't want to use the viewer, the normal Firefox Mobile behavior is used: the file is downloaded to your device and a local application is used to view the file, if you have such a viewer installed.