Manages a single persistently mapped GPU heap which is sub-allocated
inside of ring-buffer for uploads. To handle larger buffers without additional
unused heaps, ring buffers are created on-demand.
BUG=dawn:28
TEST=dawn_unittests
Change-Id: Ifc5a1b06baf8633f1e133245ac1ee76275431cc5
Reviewed-on: https://dawn-review.googlesource.com/c/3160
Commit-Queue: Bryan Bernhart <bryan.bernhart@intel.com>
Reviewed-by: Kai Ninomiya <kainino@chromium.org>
Bryan Bernhart