Add a buffer reader/writer for NTLM.

net/ntlm/BUILD.gn

+# Copyright 2017 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.
+
+source_set("ntlm") {
+  sources = [
+    "ntlm_buffer_reader.cc",
+    "ntlm_buffer_reader.h",
+    "ntlm_buffer_writer.cc",
+    "ntlm_buffer_writer.h",
+    "ntlm_constants.h",
+  ]
+  deps = [
+    "//base",
+  ]
+}
+
+source_set("ntlm_unittests") {
+  testonly = true
+  sources = [
+    "ntlm_buffer_reader_unittest.cc",
+    "ntlm_buffer_writer_unittest.cc",
+  ]
+  deps = [
+    ":ntlm",
+    "//base",
+    "//testing/gtest",
+  ]
+}