Basic UkmService implementation

components/ukm/persisted_logs_metrics_impl.cc

+// Copyright 2016 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/persisted_logs_metrics_impl.h"
+
+#include "base/metrics/histogram_macros.h"
+
+namespace ukm {
+
+metrics::PersistedLogs::LogReadStatus
+PersistedLogsMetricsImpl::RecordLogReadStatus(
+    metrics::PersistedLogs::LogReadStatus status) {
+  UMA_HISTOGRAM_ENUMERATION("UKM.PersistentLogRecall.Status",
+                            status, metrics::PersistedLogs::END_RECALL_STATUS);
+  return status;
+}
+
+void PersistedLogsMetricsImpl::RecordCompressionRatio(
+    size_t compressed_size, size_t original_size) {
+  UMA_HISTOGRAM_PERCENTAGE(
+      "UKM.ProtoCompressionRatio",
+      static_cast<int>(100 * compressed_size / original_size));
+}
+
+void PersistedLogsMetricsImpl::RecordDroppedLogSize(size_t size) {
+  UMA_HISTOGRAM_COUNTS("UKM.UnsentLogs.Dropped.Size",

[rkaplow, 2017/01/02 23:23:03]

nit, we should use _number for these macros. Looking at the UMA ones, 1M (which
this is) seems good

[Steven Holte, 2017/01/03 21:16:03]

Done.

+                       static_cast<int>(size));
+}
+
+void PersistedLogsMetricsImpl::RecordDroppedLogsNum(int dropped_logs_num) {
+  UMA_HISTOGRAM_COUNTS("UKM.UnsentLogs.Dropped", dropped_logs_num);

[rkaplow, 2017/01/02 23:23:03]

Looking at the UMA ones, I'd suggest using 10000 is probably ok

[Steven Holte, 2017/01/03 21:16:03]

Done.

+}
+
+}  // namespace ukm