Add option to export tracing events to ETW.

base/trace_event/BUILD.gn

Index: base/trace_event/BUILD.gn
diff --git a/base/trace_event/BUILD.gn b/base/trace_event/BUILD.gn
index 479a918484322712ffaef6d261584225418a7c93..d30e95b0e0c52e703b25b14157006165314ad7b0 100644
--- a/base/trace_event/BUILD.gn
+++ b/base/trace_event/BUILD.gn
@@ -25,6 +25,8 @@ source_set("trace_event") {
     "trace_event_android.cc",
     "trace_event_argument.cc",
     "trace_event_argument.h",
+    "trace_event_etw_export_win.cc",
+    "trace_event_etw_export_win.h",
     "trace_event_impl.cc",
     "trace_event_impl.h",
     "trace_event_impl_constants.cc",
@@ -55,6 +57,10 @@ source_set("trace_event") {
     "//base/third_party/dynamic_annotations",
   ]
 
+  if (is_win) {
+    deps += [ "//base/trace_event/etw_manifest:chrome_events_win" ]
+  }
+
   allow_circular_includes_from = [
     "//base/debug",
     "//base/memory",