media/base: Update WritableUnalignedMapping constructor.

Use the base::UnsafeSharedMemoryRegion constructor which avoids a mojo
dependency. Several media tests are built without mojo support.

Bug: 795291
Change-Id: If754e6111189e8944997550f00e3ed7ef9fde1c3
Reviewed-on: https://chromium-review.googlesource.com/1190243
Reviewed-by: Dan Sanders <sandersd@chromium.org>
Commit-Queue: Matthew Cary <mattcary@chromium.org>
Cr-Commit-Position: refs/heads/master@{#588808}
1 file changed