Migrate MediaStreamManager::GenerateStreamCallback to BindOnce

Bug: 714018
Change-Id: I6424da4665e0f5e4bdb8ad03b30ad5ff41d28b1f
Reviewed-on: https://chromium-review.googlesource.com/1061813
Reviewed-by: Emircan Uysaler <emircan@chromium.org>
Commit-Queue: Mark Pilgrim <pilgrim@chromium.org>
Cr-Commit-Position: refs/heads/master@{#559147}
3 files changed