gpu::ShareableImageManager has two main tasks:
1) Allocate new ShareableImageBackings, choosing the correct type based on usage params.
2) Provides a mapping from gpu::Mailbox to gpu::ShareableImageBacking.
This bug tracks the basic implementation which will only handle simple GL <> GL handoff cases.
See https://docs.google.com/document/d/12qYPeN819JkdNGbPcKBA0rfPXSOIE3aIaQVrAZ4I1lM/edit#bookmark=id.ofshur2m631h for context.
See issue 870116 for the interface which exposes this manager.
Comment 1 by ericrk@chromium.org
, Oct 1