headless: Add a Maybe-type

headless/BUILD.gn

Index: headless/BUILD.gn
diff --git a/headless/BUILD.gn b/headless/BUILD.gn
index 0f59cabd72eb81aa55cc82f793d89a64dfd6ccd9..c035c2599f406c857a196983b28abda4eefe2e5e 100644
--- a/headless/BUILD.gn
+++ b/headless/BUILD.gn
@@ -84,6 +84,7 @@ static_library("headless_lib") {
     "public/headless_browser.h",
     "public/headless_export.h",
     "public/headless_web_contents.h",
+    "public/util/maybe.h",
   ]
 
   deps = [
@@ -110,6 +111,19 @@ group("headless_tests") {
 
   deps = [
     ":headless_browsertests",
+    ":headless_unittests",
+  ]
+}
+
+test("headless_unittests") {
+  sources = [
+    "public/util/maybe_unittest.cc",
+  ]
+
+  deps = [
+    "//base/test:run_all_unittests",
+    "//base/test:test_support",
+    "//testing/gtest",
   ]
 }