Fix deadlock in render thread when Bitmap.prepareToDraw is invoked

Fix a deadlock with Skia pipelines, caused by calling
Bitmap::getSkBitmap from render thread.

Test: built and booted an image. Ran recent apps activity.
bug: 35060578
bug: 34926691
Change-Id: Iaf7957b955d938b722b153d72ad832ae5d50e86f