Reporting: Implement garbage collector.

net/reporting/reporting_garbage_collector.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 NET_REPORTING_REPORTING_GARBAGE_COLLECTOR_H_
+#define NET_REPORTING_REPORTING_GARBAGE_COLLECTOR_H_
+
+#include "base/macros.h"
+#include "base/time/time.h"
+#include "net/base/net_export.h"
+
+namespace net {
+
+class ReportingCache;
+
+// Removes reports that have remained undelivered for too long or that have been
+// included in too many failed delivery attempts. Also, removes reports on
+// network changes, if so configured.
+class NET_EXPORT ReportingGarbageCollector {
+ public:
+  struct Policy {
+    // How long a report can remain undelivered before being GCed.
+    base::TimeDelta report_max_age;
+
+    // How many times delivery of a report can fail before the report will be
+    // GCed.
+    int report_max_attempts;
+
+    // Whether reports are allowed to persist across network changes.
+    bool report_persist_across_network_changes;
+  };
+
+  static void CollectGarbage(ReportingCache* cache,
+                             const Policy& policy,
+                             base::TimeTicks now,
+                             bool network_changed);
+
+ private:
+  DISALLOW_IMPLICIT_CONSTRUCTORS(ReportingGarbageCollector);
+};
+
+}  // namespace net
+
+#endif  // NET_REPORTING_REPORTING_GARBAGE_COLLECTOR_H_