Chromecast: adds handler to log metrics from external processes.

chromecast/browser/metrics/external_metrics.h

+// 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 CHROMECAST_BROWSER_METRICS_EXTERNAL_METRICS_H_
+#define CHROMECAST_BROWSER_METRICS_EXTERNAL_METRICS_H_
+
+#include <string>
+
+#include "base/macros.h"
+#include "base/memory/weak_ptr.h"
+
+namespace metrics {
+class MetricSample;
+}  // namespace metrics
+
+namespace chromecast {
+namespace metrics {
+
+class CastStabilityMetricsProvider;
+
+// ExternalMetrics service allows processes outside of the Chromecast browser
+// process to upload metrics via reading/writing to a known shared file.
+class ExternalMetrics {
+ public:
+  explicit ExternalMetrics(CastStabilityMetricsProvider* stability_provider);
+  ~ExternalMetrics();
+
+  // Begins external data collection. Calls to RecordAction originate in the
+  // File thread but are executed in the UI thread.
+  void Start();
+
+ private:
+  // The max length of a message (name-value pair, plus header)
+  static const int kMetricsMessageMaxLength = 1024;  // be generous
+
+  // Passes an action event to the UMA service.
+  void RecordAction(const std::string& action_name);
+
+  // Records an external crash of the given string description.
+  void RecordCrash(const std::string& crash_kind);
+
+  // Records a sparse histogram. |sample| is expected to be a sparse histogram.
+  void RecordSparseHistogram(const ::metrics::MetricSample& sample);
+
+  // Collects external events from metrics log file.  This is run at periodic
+  // intervals.
+  //
+  // Returns the number of events collected.
+  int CollectEvents();
+
+  // Calls CollectEvents and reschedules a future collection.
+  void CollectEventsAndReschedule();
+
+  // Schedules a metrics event collection in the future.
+  void ScheduleCollector();
+
+  // Reference to stability metrics provider, for reporting external crashes.
+  CastStabilityMetricsProvider* stability_provider_;
+
+  // File used by libmetrics to send metrics to the browser process.
+  std::string uma_events_file_;
+
+  base::WeakPtrFactory<ExternalMetrics> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(ExternalMetrics);
+};
+
+}  // namespace metrics
+}  // namespace chromecast
+
+#endif  // CHROMECAST_BROWSER_METRICS_EXTERNAL_METRICS_H_