Fix some issues around the two-phase DataPipe read API.

- The ALL_OR_NONE flag was never supported by the implementation, so make it
  an error to pass it to BeginRead.
- It doesn't make sense to pass in how many bytes to read to
  BeginReadData, so correctly document this as an out-only parameter.
- Update unit tests to no longer incorrectly attempt to use ALL_OR_NONE.

Change-Id: I23031d454bc157500664224d3658650ee77d7b22
Reviewed-on: https://chromium-review.googlesource.com/562518
Reviewed-by: Ken Rockot <rockot@chromium.org>
Commit-Queue: Marijn Kruisselbrink <mek@chromium.org>
Cr-Commit-Position: refs/heads/master@{#484835}

CrOS-Libchrome-Original-Commit: 801d8de7fb0219622a9e653220a11a827ecbed8a
4 files changed
tree: dbb10afc0a5013727ba2d68011546da9494eb32e
  1. base/
  2. build/
  3. components/
  4. dbus/
  5. device/
  6. ipc/
  7. mojo/
  8. testing/
  9. third_party/
  10. ui/