Adding synthetic field trial for DataReductionProxyEnabled

chrome/browser/metrics/metrics_service_accessor.cc

Index: chrome/browser/metrics/metrics_service_accessor.cc
diff --git a/chrome/browser/metrics/metrics_service_accessor.cc b/chrome/browser/metrics/metrics_service_accessor.cc
index e7e8c20dccb7bd42ef212e5d076c7d48938879da..6d2539fdc82ae0c6348d816055fa44be6ef36b85 100644
--- a/chrome/browser/metrics/metrics_service_accessor.cc
+++ b/chrome/browser/metrics/metrics_service_accessor.cc
@@ -7,6 +7,7 @@
 #include "chrome/browser/browser_process.h"
 #include "components/metrics/metrics_service.h"
 #include "components/metrics/metrics_service_observer.h"
+#include "components/variations/metrics_util.h"
 
 // static
 void MetricsServiceAccessor::AddMetricsServiceObserver(
@@ -22,3 +23,17 @@ void MetricsServiceAccessor::RemoveMetricsServiceObserver(
   if (metrics_service)
     metrics_service->RemoveObserver(observer);
 }
+
+// static
+bool MetricsServiceAccessor::RegisterSyntheticFieldTrial(
+    MetricsService* metrics_service,
+    const std::string& trial,
+    const std::string& group) {
+  if (metrics_service) {

[Alexei Svitkine (slow), 2014/07/30 21:33:31]

Nit: Instead do an early return if the service is nil (reverse the if).

[megjablon, 2014/07/30 21:42:50]

Done.

+    SyntheticTrialGroup trial_group(metrics::HashName(trial),
+                                    metrics::HashName(group));
+    metrics_service->RegisterSyntheticFieldTrial(trial_group);
+    return true;
+  }
+  return false;
+}