Create ring buffer for managing D3D uniforms.

* Adds a base class for the ring buffer (to be used by Metal as well),
  which tracks the current available space. APIs will need to
  implement creation of the buffer in the subclass.
* The API implementation will need to store SubmitData on command buffer
  submit, and then pass it to finishSubmit when the command buffer
  finishes.

Change-Id: I4cc5e4a72d259ee9d15dac0e964819d4562da3d7
Bug: skia:9935
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/291936
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Jim Van Verth <jvanverth@google.com>
15 files changed