[Tracing] Add metadata filter

chrome/browser/tracing/chrome_tracing_delegate.cc

Index: chrome/browser/tracing/chrome_tracing_delegate.cc
diff --git a/chrome/browser/tracing/chrome_tracing_delegate.cc b/chrome/browser/tracing/chrome_tracing_delegate.cc
index 67b844b39a7927baff801b93e527a330dabbea5c..48cf9e3bae60c22944156b77a3c57fc17f2260d3 100644
--- a/chrome/browser/tracing/chrome_tracing_delegate.cc
+++ b/chrome/browser/tracing/chrome_tracing_delegate.cc
@@ -15,6 +15,7 @@
 #include "chrome/browser/ui/browser_list.h"
 #include "chrome/browser/ui/browser_otr_state.h"
 #include "chrome/common/pref_names.h"
+#include "chrome/common/trace_event_args_whitelist.h"
 #include "components/metrics/metrics_pref_names.h"
 #include "components/variations/active_field_trials.h"
 #include "content/public/browser/background_tracing_config.h"
@@ -150,3 +151,8 @@ void ChromeTracingDelegate::GenerateMetadataDict(
 
   metadata_dict->Set("field-trials", variations_list.Pass());
 }
+
+content::MetadataFilterPredicate
+ChromeTracingDelegate::GetMetadataFilterPredicate() {
+  return base::Bind(&IsMetadataWhitelisted);
+}