[DO NOT COMMIT] Re-use the dafsa code for s-w-r histograms

net/base/swr_histogram_domains/BUILD.gn

Index: net/base/swr_histogram_domains/BUILD.gn
diff --git a/net/base/swr_histogram_domains/BUILD.gn b/net/base/swr_histogram_domains/BUILD.gn
new file mode 100644
index 0000000000000000000000000000000000000000..5e721be810ad86e6f37fcb40a03da972205929a1
--- /dev/null
+++ b/net/base/swr_histogram_domains/BUILD.gn
@@ -0,0 +1,18 @@
+# Copyright 2015 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+action_foreach("swr_histogram_domains") {
+  script = "//net/tools/dafsa/make_dafsa.py"
+  sources = [
+    "swr_histogram_domains.gperf",
+  ]
+  outputs = [
+    "${target_gen_dir}/{{source_name_part}}-inc.cc",
+  ]
+  args = [
+    "{{source}}",
+    rebase_path("${target_gen_dir}/{{source_name_part}}-inc.cc",
+                root_build_dir),
+  ]
+}