Use SharedImageInterface in GLOutputSurfaceOffscreen.

A gpu::Mailbox is needed to do something useful with the texture in
GLOutputSurfaceOffscreen. Convert it to use SharedImageInterface to
generate a gpu::Mailbox and then GL texture from that.

Bug: 601869
Change-Id: Id7da76e06bf119bc0d679132330b75bc1662836a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1585059
Reviewed-by: Jonathan Backer <[email protected]>
Commit-Queue: kylechar <[email protected]>
Cr-Commit-Position: refs/heads/master@{#654489}
2 files changed