setPictureInPictureChangeHandler

Install the sink the renderer reports picture-in-picture transitions UP through.

The return path for setPictureInPicture. A renderer that can observe the host's picture-in-picture state itself — OverlayAdRenderer in ads-sdk-runtime watches the Activity it can reach from its own Context — reports changes here, so the orchestrator learns about a transition the VIEWER started (the system PiP button, or the swipe-home gesture on an auto-PiP Activity) without the host app wiring anything.

That is the whole point: this SDK is an add-on, and an integrator should not have to forward Activity.onPictureInPictureModeChanged for break layout to be correct. Web and iOS have always detected it themselves; Android was the outlier.

The orchestrator's OptiViewAds.setPictureInPicture is idempotent, so a host that ALSO forwards the callback costs nothing — whichever path observes the change first wins and the other is a no-op. Default no-op, like the other optional hooks.