Earthbent Artifact Creature and Gisa, Glorious Resurrector interaction.

Here's the scenario:

Players in APNAP order are A, B, C, D. Player A attacks Player B. Player B blocks with an earthbent 0/1 [[Ornithopter]] ( Earthbent by Toph, who is on the battlefield). Player D has [[Gisa, Glorious Resurrector]] on the battlefield.

Who controls the ornithopter when it becomes Player D's beginning of upkeep?