This removes the CommandBufferBuilder and copies all the logic into
CommandEncoderBase instead. No changes were done to the logic except for
the implementation of CommandEncoderBase::HandleError and Finish.
BUG=dawn:8
Change-Id: I7b6f44c3cf501477422f067bd277cef470073860
Reviewed-on: https://dawn-review.googlesource.com/c/4820
Reviewed-by: Austin Eng <enga@chromium.org>
Reviewed-by: Kai Ninomiya <kainino@chromium.org>
Commit-Queue: Corentin Wallez <cwallez@chromium.org>