gpu: Create scaffolding for SharedImageBackingOzone

This CL introduces a NativePixmap-based SharedImageBacking for use by
ChromeOS to support WebGPU. This only creates a skeleton for
SharedImageBackingOzone in an effort to split up code reviews; the
SharedImageBacking methods are neither implemented nor called.

Bug: 1023997,996470
Change-Id: Id4e8ba3079df8af609f883b61ffe6e54975e075b
Commit-Queue: Brian Ho <>
Reviewed-by: Robert Kroeger <>
Reviewed-by: Khushal <>
Reviewed-by: Eric Karl <>
Cr-Commit-Position: refs/heads/master@{#721189}
3 files changed