Update DDL test harness to use backendTextures to back tiles (take 2)

This better matches Chrome's use of DDLs.

With path, image, and text draws stripped out, here is the perf impact of this change:

           before CL   after CL
w/ DDLs      7.792      1.038
w/o DDLs     0.800      0.876

This perf improvement (in the DDL case) is from backend texture wrapping SkSurfaces being created w/o initialization. The prior method of SkSurface creation was resulting in double clearing of all the surfaces.

This perf improvement won't be seen by Chrome since they've always being using wrapped backend texture SkSurfaces.

TBR=bsalomon@google.com

Bug: 1056730
Change-Id: Ic04d322cad96df845e75437211208495862c6555
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/283866
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
5 files changed