It seems for pay.ebay.com, for some reason people prefer to type their credit card. What was surprising was that upstream was also not triggered for these pages. So unless there is a bug I imagine people prefer to type their cards unusually large number of times for ebay. 

Also before submitting the formsignature becomes 0 so probably we don't infer form submits correctly to trigger the save card prompt.

See more discussion on - https://groups.google.com/a/google.com/forum/#!searchin/chrome-autofill/An$20interesting$20analysis$20for%7Csort:date/chrome-autofill/yg_mnfujpHM/3Fe_RUaKAAAJ