Add backend GPU objects to fiddle app

TBR=bsalomon@google.com
Change-Id: I8876a4657f837436322150925233e0f36c91e8f0
Reviewed-on: https://skia-review.googlesource.com/72641
Commit-Queue: Robert Phillips <robertphillips@google.com>
Reviewed-by: Greg Daniel <egdaniel@google.com>
Reviewed-by: Cary Clark <caryclark@google.com>
diff --git a/BUILD.gn b/BUILD.gn
index 2a8b8d3..6e24d3d 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -904,6 +904,7 @@
       testonly = true
       deps = [
         ":flags",
+        ":gpu_tool_utils",
         ":skia",
         ":skia.h",
       ]