Extend accepted functors on base::Bind{Once,Repeating}

This CL allows empty functors on base::BindOnce and base::Repeating, and
adds base::BindLambdaForTesting that is a test-only variant of Bind that
binds any callable object to a RepeatingCallback.

Bug: 789805
Change-Id: I7fa34acd2a6b79e8c26d3f6ded67e91bd8d6b966
Reviewed-on: https://chromium-review.googlesource.com/798817
Commit-Queue: Taiju Tsuiki <tzik@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#521192}

CrOS-Libchrome-Original-Commit: f98654bbf86a0d88a72ed9a6fcef80931fd5e977
4 files changed
tree: a828a3388f6da7f680e9350d4c3561779c2c951e
  1. base/
  2. build/
  3. components/
  4. dbus/
  5. device/
  6. ipc/
  7. mojo/
  8. testing/
  9. third_party/
  10. ui/