Allow one-time randomization in field trials to work even if metrics are disabled.

chrome/browser/metrics/metrics_service.cc

Index: chrome/browser/metrics/metrics_service.cc
diff --git a/chrome/browser/metrics/metrics_service.cc b/chrome/browser/metrics/metrics_service.cc
index 19d1808409a1a0bc2506591355e8310712d0d883..5c6be0588ef5f0cbc4aed34948e890f491301e44 100644
--- a/chrome/browser/metrics/metrics_service.cc
+++ b/chrome/browser/metrics/metrics_service.cc
@@ -479,6 +479,21 @@ std::string MetricsService::GetClientId() {
   return client_id_;
 }
 
+std::string MetricsService::GetClientIdNonEmpty() {
+  PrefService* pref = g_browser_process->local_state();
+  DCHECK(pref);
+  std::string client_id = pref->GetString(prefs::kMetricsClientID);
+  if (client_id.empty()) {
+    client_id = GenerateClientID();
+    pref->SetString(prefs::kMetricsClientID, client_id);
+
+    // Might as well make a note of how long this ID has existed
+    pref->SetString(prefs::kMetricsClientIDTimestamp,
+                    base::Int64ToString(Time::Now().ToTimeT()));
+  }
+  return client_id;
+}
+
 void MetricsService::SetRecording(bool enabled) {
   DCHECK(IsSingleThreaded());
 
@@ -487,17 +502,7 @@ void MetricsService::SetRecording(bool enabled) {
 
   if (enabled) {
     if (client_id_.empty()) {
-      PrefService* pref = g_browser_process->local_state();
-      DCHECK(pref);
-      client_id_ = pref->GetString(prefs::kMetricsClientID);
-      if (client_id_.empty()) {
-        client_id_ = GenerateClientID();
-        pref->SetString(prefs::kMetricsClientID, client_id_);
-
-        // Might as well make a note of how long this ID has existed
-        pref->SetString(prefs::kMetricsClientIDTimestamp,
-                        base::Int64ToString(Time::Now().ToTimeT()));
-      }
+      client_id_ = GetClientIdNonEmpty();
     }
     child_process_logging::SetClientId(client_id_);
     StartRecording();