Convert ImmersiveOverlay to new Mojo types

This CL converts ImmersiveOverlay{Ptr, Request} in chrome and
device to the new Mojo type, and use
pending_receiver<ImmersiveOverlay> in isolated_xr_service.mojom.

Bug: 955171
Change-Id: I6bffe1a07b9e2240834e69d2ebcada64b8fdd7fb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1847452
Commit-Queue: Miyoung Shin <myid.shin@igalia.com>
Reviewed-by: Sam McNally <sammc@chromium.org>
Reviewed-by: Klaus Weidner <klausw@chromium.org>
Reviewed-by: Piotr Bialecki <bialpio@chromium.org>
Reviewed-by: Ken Rockot <rockot@google.com>
Cr-Commit-Position: refs/heads/master@{#704513}
13 files changed