Add SharedImageInterface, Proxy, and Stub.

SharedImageInterface is a minimal interface to allocate and destroy
mailbox resources. It is independent of GL, stateless, thread-safe and
expresses direct ownership of the resources.
SharedImageInterfaceProxy and SharedImageStub implement
SharedImageInterface over IPC.

Note: currently SharedImageInterfaceProxy sends an IPC for creating and
destroying shared images, but this will be merged into the multi-flush
IPC in a follow-up.

Bug: 870116
Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel;luci.chromium.try:linux_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;luci.chromium.try:win_optional_gpu_tests_rel
Change-Id: I8f0b86957fab34a1a93f0b2ada8590a048e81724
Reviewed-on: https://chromium-review.googlesource.com/1164168
Commit-Queue: Antoine Labour <piman@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: Victor Miura <vmiura@chromium.org>
Cr-Commit-Position: refs/heads/master@{#582203}
20 files changed