Google Chrome has its own nifty PDF viewer plug-in but there are some situations where you may not want to use it. The default Google Chrome PDF viewer does not give you any print scaling options. It defaults to printing a scaled page. This can be a problem if you are printing a form that must appear at its originally designed size (ie: IRS forms, Avery labels, currency).
You can easily disable the plug-in to allow Adobe Reader or Adobe Acrobat handle the online PDF file.