Reporting: Implement serializer.

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 <memory>
 
 #include "net/base/net_export.h"
 
 namespace base {
 class Timer;
 }  // namespace base
 
 namespace net {
 
 class ReportingContext;
 
 // Removes reports that have remained undelivered for too long or that have been
 // included in too many failed delivery attempts.
 class NET_EXPORT ReportingGarbageCollector {
  public:
+  // Creates a ReportingGarbageCollector. |context| must outlive the garbage
+  // collector.
   static std::unique_ptr<ReportingGarbageCollector> Create(
       ReportingContext* context);
 
   virtual ~ReportingGarbageCollector();
 
+  // Initializes the GarbageCollector, which performs an initial garbage
+  // collection pass over any data already in the Cache.
+  virtual void Initialize() = 0;
+
+  // Replaces the internal Timer used for scheduling garbage collection passes
+  // with a caller-specified one so that unittests can provide a MockTimer.
   virtual void SetTimerForTesting(std::unique_ptr<base::Timer> timer) = 0;
 };
 
 }  // namespace net
 
 #endif  // NET_REPORTING_REPORTING_GARBAGE_COLLECTOR_H_