Deallocate offscreen buffer for non-HW-accel draw

Follow up to I5bc980c4dc41bc304be3c190934c1f7c55c9d244

This frees up 800KB on occam_svelte when LatinIME is in background.
Confirmed the performance effect in keyboard-bring up speed was unperceivable.

bug: 8967766
Change-Id: I0fab179c61179564bd3a0349c9825e7d61f7e1f2
2 files changed
tree: a45afce91b4d15d40397341429377a364bfd9f4a
  1. dictionaries/
  2. java/
  3. native/
  4. tests/
  5. tools/
  6. Android.mk
  7. CleanSpec.mk