Add new DDL helper files to public.bzl

Change-Id: I9243b5ed143ff7e688cd26fb8649676286a65794
Reviewed-on: https://skia-review.googlesource.com/130780
Reviewed-by: Ravi Mistry <rmistry@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
diff --git a/public.bzl b/public.bzl
index 0b2c355..0c00f74 100644
--- a/public.bzl
+++ b/public.bzl
@@ -444,6 +444,10 @@
         "tools/BigPathBench.inc",
         "tools/CrashHandler.cpp",
         "tools/CrashHandler.h",
+        "tools/DDLPromiseImageHelper.cpp",
+        "tools/DDLPromiseImageHelper.h",
+        "tools/DDLTileHelper.cpp",
+        "tools/DDLTileHelper.h",
         "tools/ProcStats.cpp",
         "tools/ProcStats.h",
         "tools/Registry.h",