mojo: expose [Un]WrapPlatformSharedMemoryRegion

This enables transitional mojo interfaces that communicate in
base::subtle::PlatformSharedMemoryRegion to interoperate with interfaces
that use a mojo handle<shared_buffer>.

Bug: 849207, 640840
Change-Id: I759a0115d1b677ebcbd335997553b705f61f00a3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1570829
Reviewed-by: Ken Rockot <rockot@google.com>
Commit-Queue: Matthew Cary <mattcary@chromium.org>
Cr-Commit-Position: refs/heads/master@{#652083}
2 files changed