Pepper: Upgrade VpnProvider* to new shared memory api.

Upgrades content::PepperVpnProviderMessageFilter (chromeos only)
and the ppapi:: side VpnProviderSharedBuffer and
VpnProviderResource to the new shared memory api.

In the current implementation, both send and receive buffers are
mapped writable, so uses of SharedMemory are replaced with
UnsafeSharedMemoryRegions. There is no functional change.

Bug: 795291
Change-Id: I19153a6d59d0ad6385423a495d736a92b4642c78
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1649325
Reviewed-by: Raymes Khoury <raymes@chromium.org>
Reviewed-by: Alex Ilin <alexilin@chromium.org>
Commit-Queue: Matthew Cary (CET) <mattcary@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#668333}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: d490a5ac8444dc63bf0ecc78e1b37802e304d5b5
3 files changed