Something is off about this.
Those chargers generate enough current to kill someone. Looking at the charger on my S7, it'll output between 1.67 and 2.0 amps. As I recall from grade school, it takes only 0.5 amps to kill a person, depending on resistance, so >= 1.67 will definitely do it, and for the sake of argument let's assume a 220v charger outputs the same or more amperage....
So that being the case...
I feel like we would have heard about this happening before. Surely someone has dropped their phone in the tub before while it was charging before this. We would be hearing about this every week.
Something is off.
Edit: Just saw the video about the frayed extension cord. That would definitely do it.