Reporting: Cap number of clients in cache.

net/reporting/reporting_delivery_agent.cc

Index: net/reporting/reporting_delivery_agent.cc
diff --git a/net/reporting/reporting_delivery_agent.cc b/net/reporting/reporting_delivery_agent.cc
index 209ea8f60d47d975816eed3c88a8a3887b534b3a..d875f468b88c2200f6a5df4c1594c34c93607202 100644
--- a/net/reporting/reporting_delivery_agent.cc
+++ b/net/reporting/reporting_delivery_agent.cc
@@ -135,6 +135,8 @@ class ReportingDeliveryAgentImpl : public ReportingDeliveryAgent,
         continue;
       }
 
+      cache()->MarkClientUsed(origin_group.first, endpoint_url);
+
       endpoint_reports[endpoint_url].insert(
           endpoint_reports[endpoint_url].end(), it.second.begin(),
           it.second.end());