Add UMA histogram data representing the Synced Notifications feature.

chrome/browser/notifications/sync_notifier/synced_notification_stats.cc

+// Copyright (c) 2013 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/notifications/sync_notifier/synced_notification_stats.h"
+
+#include <string>
+
+#include "base/metrics/histogram.h"
+#include "content/public/browser/user_metrics.h"
+
+namespace notifier {
+
+SyncedNotificationStats::SyncedNotificationStats() {}
+
+SyncedNotificationStats::SyncedNotificationStats(
+    const std::string& id) : id_(id) {}
+
+SyncedNotificationStats::~SyncedNotificationStats() {}
+
+void SyncedNotificationStats::CollectAction(
+    SyncedNotificationActionType type) {
+  DCHECK(!id_.empty());
+
+  UMA_HISTOGRAM_ENUMERATION("SyncedNotifications.Actions",
+                            type,
+                            SYNCED_NOTIFICATION_ACTION_COUNT);
+}
+
+}  // namespace notifier