You probably need to use the other modifier keys. But it's weird... it's not even a PC-101! I guess Google has really gone back to the roots... PC/XT or PC/AT :P

PC/XT keyboard: http://upload.wikimedia.org/wikipedia/commons/8/85/IBM_5150_...

Discussion briefly mentions PgUp: https://plus.google.com/+JeffJarvis/posts/g9gcXLPuVVQ