Reporting: Cap number of reports in cache.

net/reporting/reporting_policy.h

Index: net/reporting/reporting_policy.h
diff --git a/net/reporting/reporting_policy.h b/net/reporting/reporting_policy.h
index c400bfff452d4f2eb86e3b833d8cee7ea224fac7..98e1a4a5e4ec0481942559b6b668f3875f1aafc0 100644
--- a/net/reporting/reporting_policy.h
+++ b/net/reporting/reporting_policy.h
@@ -18,6 +18,9 @@ struct NET_EXPORT ReportingPolicy {
   ReportingPolicy(const ReportingPolicy& other);
   ~ReportingPolicy();
 
+  // Maximum number of reports to queue before evicting the oldest.
+  size_t max_report_count;
+
   // Minimum interval at which to attempt delivery of queued reports.
   base::TimeDelta delivery_interval;