The viewer.js can not take online PDF stream.

By default, viewer.js has:

var kDefaultURL = 'compressed.tracemonkey-pldi-09.pdf';

Now use PDF stream:
http://www.liferay.com/documents/31578/11925632/sample.pdf

as

var kDefaultURL = 'http://www.liferay.com/documents/31578/11925632/sample.pdf';

In FireFox 9.0.1 and Chrome 16.0.912.63 , it throws errors:

"
PDF.JS Build: 9161c2e
Message: Unexpected server response of 0.
".