Revert "Optimize magnifier viewport drawing"

This reverts commit 1d006f483e1f4f36720424b948d819a76f065956.

Reason for revert: https://buganizer.corp.google.com/issues/318327737, https://buganizer.corp.google.com/issues/318328468

Change-Id: I057397ea972e72e48433ad0bf809d82ab5d9e950
2 files changed