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The notable changes from using the updated ABI are the use of read
fences returned by the framework to synchronize release of resources in
transaction acks.

The current code has some shortcomings in terms of potentially reading
the media buffers from GL (display compositor) and/or the framework
(system compositor). We currently always bind every new buffer to a
texture with an EGL fence wait, which is unnecessary if the buffer will
be passed to the system compositor. On the other end, we always and only
generate a read fence from GL that the AImageReader_deleteasync uses if
the current image has no external refs when a new image is acquired.
Ideally we should wait on read fences from GL and the framework if the
buffer was read by both (possible since the overlay decision could change
every frame), and only generate a read fence from GL if the buffer was
used by the display compositor.

All the above fence synchronization is meant to be correctly handled
using SharedImages, which can handle a buffer being imported by different
consumers and generating/synchronizing read fences bases on which API the
buffer is read by. Ensuring that these cases are handled correctly is left
until media is switched to Shared Images.

TBR=nyquist@chromium.org
R=liberato@chromium.org, piman@chromium.org

Bug: 889328
Change-Id: Ic9f49420540249c06943fd62f6fcba8830c6ccac
Reviewed-on: https://chromium-review.googlesource.com/c/1434918
Commit-Queue: Khushal <khushalsagar@chromium.org>
Reviewed-by: Antoine Labour <piman@chromium.org>
Reviewed-by: Frank Liberato <liberato@chromium.org>
Auto-Submit: Khushal <khushalsagar@chromium.org>
Cr-Commit-Position: refs/heads/master@{#626799}