Refactored Texture2D, separated out D3D logic BUG=angle:688 Change-Id: I93c2ff0b125278234d61324844b79cc58135d4d8 Reviewed-on: https://chromium-review.googlesource.com/207675 Reviewed-by: Shannon Woods <shannonwoods@chromium.org> Tested-by: Brandon Jones <bajones@chromium.org>