Reland "Open MessagePumpLibevent's pipe with O_CLOEXEC"

This prevents the pipe's fds from being leaked into child processes.

TEST=git cl try
BUG=653930

Review-Url: https://codereview.chromium.org/2398253004
Cr-Commit-Position: refs/heads/master@{#424030}


CrOS-Libchrome-Original-Commit: 80c77bfd8614a09e83b618a819bef076508bdcf8
3 files changed
tree: f4e474f7c6e10625e165467fda184bf1286a0294
  1. base/
  2. build/
  3. components/
  4. dbus/
  5. device/
  6. ipc/
  7. mojo/
  8. testing/
  9. third_party/
  10. ui/