Refactor UKM interface for mojo-ification

components/ukm/ukm_entry.h

-// Copyright 2017 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 COMPONENTS_UKM_UKM_ENTRY_H_
-#define COMPONENTS_UKM_UKM_ENTRY_H_
-
-#include <string>
-#include <vector>
-
-#include "base/macros.h"
-
-namespace ukm {
-
-class Entry;
-class UkmEntryBuilder;
-
-// One UkmEntry contains metrics for a specific source and event. It is
-// connected to a UkmSource by the source ID. The event can be user defined.
-// One example is "PageLoad". Each UkmEntry can have a list of metrics, each of
-// which consist of a metric name and value. When the entry is serialized to the
-// proto message, the event and metric names will be hashed by
-// base::HashMetricName.
-//
-// To build UkmEntry objects, please use UkmEntryBuilder.
-class UkmEntry {
- public:
-  // Serializes the members of the class into the supplied proto.
-  void PopulateProto(Entry* proto_entry) const;
-
-  int32_t source_id() const { return source_id_; }
-  uint64_t event_hash() const { return event_hash_; }
-
-  ~UkmEntry();
-
- private:
-  friend UkmEntryBuilder;
-
-  UkmEntry(int32_t source_id, const char* event_name);
-
-  const int32_t source_id_;
-  const uint64_t event_hash_;
-  std::vector<std::pair<uint64_t, int64_t>> metrics_;
-
-  DISALLOW_COPY_AND_ASSIGN(UkmEntry);
-};
-
-}  // namespace ukm
-
-#endif  // COMPONENTS_UKM_UKM_ENTRY_H_