Refactor UKM interface for mojo-ification

components/ukm/ukm_entry_builder.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_BUILDER_H
-#define COMPONENTS_UKM_UKM_ENTRY_BUILDER_H
-
-#include <string>
-
-#include "base/macros.h"
-#include "components/ukm/ukm_service.h"
-
-namespace ukm {
-
-class UkmEntry;
-class UkmService;
-
-// The builder that builds UkmEntry and adds it to UkmService.
-// The example usage is:
-//
-// {
-//   unique_ptr<UkmEntryBuilder> builder =
-//       ukm_service->GetEntryBuilder(source_id, "PageLoad");
-//   builder->AddMetric("NavigationStart", navigation_start_time);
-//   builder->AddMetric("ResponseStart", response_start_time);
-//   builder->AddMetric("FirstPaint", first_paint_time);
-//   builder->AddMetric("FirstContentfulPaint", fcp_time);
-// }
-//
-// When there exists an added metric, the builder will automatically add the
-// UkmEntry to UkmService upon destruction when going out of scope.
-class UkmEntryBuilder {
- public:
-  // Add metric to the entry. A metric contains a metric name and value.
-  void AddMetric(const char* metric_name, int64_t value);
-
-  ~UkmEntryBuilder();
-
- private:
-  friend class UkmService;
-
-  UkmEntryBuilder(const UkmService::AddEntryCallback& callback,
-                  int32_t source_id,
-                  const char* event_name);
-
-  UkmService::AddEntryCallback add_entry_callback_;
-  std::unique_ptr<UkmEntry> entry_;
-
-  DISALLOW_COPY_AND_ASSIGN(UkmEntryBuilder);
-};
-
-}  // namespace ukm
-
-#endif  // COMPONENTS_UKM_UKM_ENTRY_BUILDER_H