Land prep work to enable NaCl in the Linux x64 GN builds.

ui/events/BUILD.gn

Index: ui/events/BUILD.gn
diff --git a/ui/events/BUILD.gn b/ui/events/BUILD.gn
index f68925ee87f2ebad2f968afc88904ec5d52df457..e76dce50a8baa9739db39226954aeddd15917f32 100644
--- a/ui/events/BUILD.gn
+++ b/ui/events/BUILD.gn
@@ -347,3 +347,14 @@ test("events_unittests") {
     sources += [ "gestures/gesture_provider_aura_unittest.cc" ]
   }
 }
+
+if (is_nacl) {
+  static_library("latency_info") {
+    sources = [
+      "latency_info.cc",
+      "latency_info.h",
+      "ipc/latency_info_param_traits.cc",
+      "ipc/latency_info_param_traits.h",
+    ]
+  }
+}