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This change is a prerequisite for having buffer manager
to handle frame callbacks.

Also, each window will be backed with own buffer manager,
which is needed to ease handling of the frame callbacks.

Now, zwp_linux_dmabuf Wayland factory is wrapped around
WaylandZwpLinuxDmabuf and receives requests to create
buffers backed by dmabuf file descriptor. Returns
a wl_buffer on success via a provided callback. If
failed, nullptr is returned.

Bug: 943096
Change-Id: I85cff3ad7a12e26a4380b87d2933af377c436e4d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1539700
Commit-Queue: Maksim Sisov <msisov@igalia.com>
Reviewed-by: Robert Kroeger <rjkroege@chromium.org>
Cr-Commit-Position: refs/heads/master@{#644728}