DO NOT MERGE Updating AnimationSpec and related internal APIs to use GraphicBuffer.

- This reduces the copy of the hardware bitmap when it is
  parceled/unparceled.

Bug: 38507414
Bug: 62021436
Test: Launch Overview to/from app, ensure that the header bar shows
Test: go/wm-smoke

Change-Id: I85a9a59a0a3699d1642158061d10fddef34393c3
Signed-off-by: Winson Chung <winsonc@google.com>