Stub in more IPC attachment brokering functionality.

This CL fills in most of the logic for sending a Windows HANDLE from a
non-broker process to the broker process. This consists of several small
changes:

- Create the new IPC messages AttachmentBrokerMsg_WinHandleHasBeenBrokered and
AttachmentBrokerMsg_RequestBrokerageOfWinHandle.
- Add a sender_ member variable to AttachmentBrokerWin.
- Define the wire format for HandleAttachmentWin.
- Add logic to ChannelWin to send
AttachmentBrokerMsg_RequestBrokerageOfWinHandle for each HANDLE attachment.

BUG=466437

Review URL: https://codereview.chromium.org/1188923003

Cr-Commit-Position: refs/heads/master@{#337689}


CrOS-Libchrome-Original-Commit: eece6c3ca617b0d3c37ce137aba1d2079ab892e4
16 files changed
tree: 834f8ee6268ed4c56a8a6944cebd80ef3977867a
  1. base/
  2. build/
  3. components/
  4. dbus/
  5. device/
  6. ipc/
  7. mojo/
  8. testing/
  9. third_party/
  10. ui/