Refactor UKM interface for mojo-ification

components/ukm/public/ukm_recorder.cc

+// 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.
+
+#include "components/ukm/public/ukm_recorder.h"
+
+#include "base/atomic_sequence_num.h"
+#include "base/bind.h"
+#include "base/feature_list.h"
+#include "base/memory/ptr_util.h"
+#include "components/ukm/public/ukm_entry_builder.h"
+
+namespace ukm {
+
+const base::Feature kUkmFeature = {"Ukm", base::FEATURE_DISABLED_BY_DEFAULT};
+
+UkmRecorder::UkmRecorder() = default;
+UkmRecorder::~UkmRecorder() = default;
+
+// static
+ukm::SourceId UkmRecorder::GetNewSourceID() {
+  static base::StaticAtomicSequenceNumber seq;
+  return static_cast<ukm::SourceId>(seq.GetNext());
+}
+
+std::unique_ptr<UkmEntryBuilder> UkmRecorder::GetEntryBuilder(
+    ukm::SourceId source_id,
+    const char* event_name) {
+  return base::MakeUnique<UkmEntryBuilder>(
+      base::Bind(&UkmRecorder::AddEntry, base::Unretained(this)), source_id,
+      event_name);
+}
+
+}  // namespace ukm