[mojo-edk] Stop using the sync broker on OS X

The sync broker is only needed for sandboxed shared
buffer allocation on POSIX, but it's not needed for
Mach shared buffers.

This stops using the broker on OS X.

BUG=591742,590979

Review URL: https://codereview.chromium.org/1809363002

Cr-Commit-Position: refs/heads/master@{#381908}


CrOS-Libchrome-Original-Commit: 018a4e46c477ada7307ed5c7dad7eb58b7da75b5
2 files changed
tree: d096c370c50004a31455bc9647042763dd694469
  1. base/
  2. build/
  3. components/
  4. dbus/
  5. device/
  6. ipc/
  7. mojo/
  8. testing/
  9. third_party/
  10. ui/