Support add-on 'field trial' records.

chrome/browser/metrics/field_trial_synchronizer.cc

Index: chrome/browser/metrics/field_trial_synchronizer.cc
diff --git a/chrome/browser/metrics/field_trial_synchronizer.cc b/chrome/browser/metrics/field_trial_synchronizer.cc
index 3b3ffef02532328bcd72146c7b46b8b400c009f5..34be4b5bcaa9bb548f87ceb02044e47663e0cd28 100644
--- a/chrome/browser/metrics/field_trial_synchronizer.cc
+++ b/chrome/browser/metrics/field_trial_synchronizer.cc
@@ -8,6 +8,7 @@
 #include "base/logging.h"
 #include "base/threading/thread.h"
 #include "chrome/common/renderer_configuration.mojom.h"
+#include "components/metrics/persistent_system_profile.h"
 #include "components/variations/variations_util.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/render_process_host.h"
@@ -39,6 +40,11 @@ void FieldTrialSynchronizer::NotifyAllRenderers(
   // need to be on the UI thread.
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 
+  // Note this in the persistent profile as it will take a while for a new
+  // "complete" profile to be genereated.
+  metrics::GlobalPersistentSystemProfile::GetInstance()->SetFieldTrial(
+      field_trial_name, group_name);
+
   for (content::RenderProcessHost::iterator it(
           content::RenderProcessHost::AllHostsIterator());
        !it.IsAtEnd(); it.Advance()) {