Adding synthetic field trial for DataReductionProxyEnabled

chrome/browser/metrics/chrome_metrics_service_accessor.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/metrics/chrome_metrics_service_accessor.h"
 
 #include "base/prefs/pref_service.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/common/pref_names.h"
 #include "components/metrics/metrics_service.h"
+#include "components/variations/metrics_util.h"
 
 #if defined(OS_CHROMEOS)
 #include "chrome/browser/chromeos/settings/cros_settings.h"
 #endif
 
 // static
 bool ChromeMetricsServiceAccessor::IsMetricsReportingEnabled() {
   bool result = false;
   const PrefService* local_state = g_browser_process->local_state();
   if (local_state) {
@@ skipping 18 matching lines @@
   // Android has its own settings for metrics / crash uploading.
   const PrefService* prefs = g_browser_process->local_state();
   return prefs->GetBoolean(prefs::kCrashReportingEnabled);
 #else
   return ChromeMetricsServiceAccessor::IsMetricsReportingEnabled();
 #endif
 #else
   return false;
 #endif
 }
+
+// static
+void ChromeMetricsServiceAccessor::RegisterSyntheticFieldTrial(
+    std::string trial, std::string group) {
+  if (g_browser_process->metrics_service()) {

[bengr, 2014/07/30 19:08:22]

Would we ever not have a metrics_service? It would be nice if the caller could
know that registration was a no-op.

[megjablon, 2014/07/30 21:27:07]

g_browser_process->metrics_service() may return null

we can return false if the service is not available so the registration didn't
happen

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