sync: Introduce classes for per-type counters

sync/internal_api/public/sessions/update_counters.h

Index: sync/internal_api/public/sessions/update_counters.h
diff --git a/sync/internal_api/public/sessions/update_counters.h b/sync/internal_api/public/sessions/update_counters.h
new file mode 100644
index 0000000000000000000000000000000000000000..506d3414eec7b48d3fd2a038b77528f1868dce03
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+++ b/sync/internal_api/public/sessions/update_counters.h
@@ -0,0 +1,37 @@
+// 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.
+
+#ifndef SYNC_INTERNAL_API_PUBLIC_SESSIONS_UPDATE_COUNTERS_H_
+#define SYNC_INTERNAL_API_PUBLIC_SESSIONS_UPDATE_COUNTERS_H_
+
+#include "base/memory/scoped_ptr.h"
+#include "base/values.h"
+#include "sync/base/sync_export.h"
+
+namespace syncer {
+
+// A class to maintain counts related to the update requests and responses for
+// a particular sync type.
+struct SYNC_EXPORT_PRIVATE UpdateCounters {
+  UpdateCounters();
+  ~UpdateCounters();
+
+  scoped_ptr<base::DictionaryValue> ToValue() const;
+  std::string ToString() const;
+
+  int num_updates_received;
+  int num_reflected_updates_received;
+  int num_tombstone_updates_received;
+
+  int num_updates_applied;
+  int num_hierarchy_conflict_application_failures;
+  int num_encryption_conflict_application_failures;
+
+  int num_server_overwrites;
+  int num_local_overwrites;
+};
+
+}  // namespace syncer
+
+#endif  // SYNC_INTERNAL_API_PUBLIC_SESSIONS_UPDATE_COUNTERS_H_