Create a field test for sync sign in promo strings.

chrome/browser/ui/webui/sync_promo_trial.cc

+// Copyright (c) 2011 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/ui/webui/sync_promo_trial.h"
+
+#include "base/metrics/field_trial.h"
+#include "chrome/browser/metrics/metrics_service.h"
+#include "chrome/browser/prefs/pref_service.h"
+
+namespace {
+
+// Field trial IDs of the control and experiment groups. Though they are not
+// literally "const", they are set only once, in Activate() below. See the .h
+// file for what these groups represent.
+int g_sync_promo_experiment_a = 0;
+int g_sync_promo_experiment_b = 0;
+int g_sync_promo_experiment_c = 0;
+int g_sync_promo_experiment_d = 0;
+
+const char* kSyncPromoMsgTrialName = "SyncPromoMsg";
+
+}
+
+// static
+void SyncPromoTrial::Activate() {
+  // TODO(stevet): Verify with jeffreyc that this date (March 12, 2012) is
+  // approx 2 weeks into M17 stable.
+  scoped_refptr<base::FieldTrial> trial(
+      new base::FieldTrial(kSyncPromoMsgTrialName, 1000, "MsgA", 2012, 3, 12));
+  g_sync_promo_experiment_a = base::FieldTrial::kDefaultGroupNumber;
+
+  // Try to give the user a consistent experience, if possible.
+  if (base::FieldTrialList::IsOneTimeRandomizationEnabled())
+    trial->UseOneTimeRandomization();
+
+  // Each group has probability 0.5%, leaving the control with 98.5%.
+  g_sync_promo_experiment_b = trial->AppendGroup("MsgB", 5);
+  g_sync_promo_experiment_c = trial->AppendGroup("MsgC", 5);
+  g_sync_promo_experiment_d = trial->AppendGroup("MsgD", 5);
+}
+
+// static
+bool SyncPromoTrial::IsExperimentActive() {
+  return base::FieldTrialList::FindValue(kSyncPromoMsgTrialName) !=
+      base::FieldTrial::kNotFinalized;
+}
+
+// static
+SyncPromoTrial::Group SyncPromoTrial::GetGroup() {
+  // Promo message A is also the default value, so display it if there is no
+  // active experiment.
+  if (!IsExperimentActive())
+    return PROMO_MSG_A;
+
+  const int group = base::FieldTrialList::FindValue(kSyncPromoMsgTrialName);
+  if (group == g_sync_promo_experiment_a)
+    return PROMO_MSG_A;
+  else if (group == g_sync_promo_experiment_b)
+    return PROMO_MSG_B;
+  else if (group == g_sync_promo_experiment_c)
+    return PROMO_MSG_C;
+  else if (group == g_sync_promo_experiment_d)
+    return PROMO_MSG_D;
+
+  NOTREACHED();
+  return PROMO_MSG_A;
+}
+
+// static
+void SyncPromoTrial::RecordUserSawMessage() {
+  DCHECK(IsExperimentActive());
+  UMA_HISTOGRAM_ENUMERATION("SyncPromo.MessageDisplayed",
+                            GetGroup(),
+                            PROMO_MSG_MAX);
+}
+
+// static
+void SyncPromoTrial::RecordUserSignedIn() {
+  DCHECK(IsExperimentActive());
+  UMA_HISTOGRAM_ENUMERATION("SyncPromo.MessageOnSignIn",
+                            GetGroup(),
+                            PROMO_MSG_MAX);
+}