I googled it & it seems to be a plugin problem in chromium. Anyone have any idea how to get rid of this pesky behavior? Tqvm.
Try disabling the pdf plugin.
Open plugins in the addressbar
Got it. Disabled the default chrome pdf plugin & the popup have stopped coming. Tqvm
It seems like a vulnerability of the pdf plugin being exploit by adware. I have scan my PC with various antivirus & the result are all clean, so im not sure how the exploit "working" in vivaldi.