Add new experimental ddlbench

This intended to let us experiment w/ threaded compilation before having
to worry about upstreaming features.

Change-Id: Id9d1807de0fa16475184203d293e00bfaf5fcc01
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/373736
Commit-Queue: Robert Phillips <robertphillips@google.com>
Reviewed-by: Adlai Holler <adlai@google.com>
diff --git a/BUILD.gn b/BUILD.gn
index f62fe24..8b5c9db 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -2104,6 +2104,14 @@
         "modules/svg",
       ]
     }
+    test_app("ddlbench") {
+      sources = [ "experimental/ddlbench/ddlbench.cpp" ]
+      deps = [
+        ":flags",
+        ":skia",
+        ":tool_utils",
+      ]
+    }
 
     # optional separate library to dlopen when running CanvasStateTests.
     shared_library("canvas_state_lib") {