Convert RLZ to a buildflag header

chrome/test/BUILD.gn

Index: chrome/test/BUILD.gn
diff --git a/chrome/test/BUILD.gn b/chrome/test/BUILD.gn
index e39ee89ad082d4aeedc678b56710f07955169cdb..f33c6492448747e06f4ff50fb03dc8357bba1b3b 100644
--- a/chrome/test/BUILD.gn
+++ b/chrome/test/BUILD.gn
@@ -16,6 +16,7 @@ import("//extensions/features/features.gni")
 import("//media/media_options.gni")
 import("//ppapi/features/features.gni")
 import("//remoting/remoting_enable.gni")
+import("//rlz/features/features.gni")
 import("//services/service_manager/public/service_manifest.gni")
 import("//testing/test.gni")
 import("//ui/base/ui_features.gni")
@@ -1228,6 +1229,7 @@ test("browser_tests") {
     "//media:media_features",
     "//ppapi/features",
     "//printing/features",
+    "//rlz/features",
     "//third_party/WebKit/public:features",
   ]