Where does Google Chrome put .desktop files?
Solution 1:
Chrome creates two .desktop files, one on the desktop (in ~/Desktop) and another in ~/.local/share/applications. The latter is shown in the Dash. To find it, run
grep -ri "whatsapp" ~/.local/share/applications
E.g. mine was called chrome-hnpfjngllnobngcgfapefoaidbinmjnm-Default.desktop. I was able to edit the Icon field and have it take effect in the Dash.