Add DejaVu Sans Mono (regular) font to third_party.

third_party/dejavu-fonts-ttf-2.34/BUILD.gn

Index: third_party/dejavu-fonts-ttf-2.34/BUILD.gn
diff --git a/third_party/dejavu-fonts-ttf-2.34/BUILD.gn b/third_party/dejavu-fonts-ttf-2.34/BUILD.gn
new file mode 100644
index 0000000000000000000000000000000000000000..41cf227415475764028a8b8e93b772eab3a26798
--- /dev/null
+++ b/third_party/dejavu-fonts-ttf-2.34/BUILD.gn
@@ -0,0 +1,17 @@
+# 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.
+
+import("//mojo/tools/embed/rules.gni")
+
+embed_file("DejaVuSansMonoRegular") {
+  source = "ttf/DejaVuSansMono.ttf"
+  namespace = "font_data"
+  variable = "kDejaVuSansMonoRegular"
+}
+
+embed_file("DejaVu_license_text") {
+  source = "LICENSE"
+  namespace = "licenses"
+  variable = "kDejaVuLicenseText"
+}