This is a reland of 06ff9e97
Original change's description:
> [logging] Use OFStream for log events
> 
> This simplifies a few operations and removes the size limitations
> implied by the message buffer used.
> 
> Change-Id: I8b873a0ffa399a037ff5c2501ba4b68158810968
> Reviewed-on: https://chromium-review.googlesource.com/724285
> Commit-Queue: Camillo Bruni <cbruni@chromium.org>
> Reviewed-by: Adam Klein <adamk@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#48766}

Change-Id: Iafda1c88d9180d188d6b8bd7d03d6d27100538d8
Reviewed-on: https://chromium-review.googlesource.com/731107
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Reviewed-by: Adam Klein <adamk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48804}