Reporting: Add histograms.

net/reporting/reporting_cache.h

Index: net/reporting/reporting_cache.h
diff --git a/net/reporting/reporting_cache.h b/net/reporting/reporting_cache.h
index 1a5d31d8328c60157ddabe98c1f5311d82736027..efcfbdf63fb64731241f0ad3d6d8edb5668f48fd 100644
--- a/net/reporting/reporting_cache.h
+++ b/net/reporting/reporting_cache.h
@@ -19,6 +19,7 @@
 #include "base/values.h"
 #include "net/base/net_export.h"
 #include "net/reporting/reporting_client.h"
+#include "net/reporting/reporting_report.h"
 #include "url/gurl.h"
 #include "url/origin.h"
 
@@ -29,7 +30,6 @@ class TickClock;
 namespace net {
 
 class ReportingContext;
-struct ReportingReport;
 
 // The cache holds undelivered reports and clients (per-origin endpoint
 // configurations) in memory. (It is not responsible for persisting them.)
@@ -83,11 +83,12 @@ class NET_EXPORT ReportingCache {
   // Removes a set of reports. Any reports that are pending will not be removed
   // immediately, but rather marked doomed and removed once they are no longer
   // pending.
-  void RemoveReports(const std::vector<const ReportingReport*>& reports);
+  void RemoveReports(const std::vector<const ReportingReport*>& reports,
+                     ReportingReport::Outcome outcome);
 
   // Removes all reports. Like |RemoveReports()|, pending reports are doomed
   // until no longer pending.
-  void RemoveAllReports();
+  void RemoveAllReports(ReportingReport::Outcome outcome);
 
   // Creates or updates a client for a particular origin and a particular
   // endpoint.
@@ -165,6 +166,8 @@ class NET_EXPORT ReportingCache {
   }
 
  private:
+  void RemoveReportInternal(const ReportingReport* report);
+
   const ReportingReport* FindReportToEvict() const;
 
   void AddClient(std::unique_ptr<ReportingClient> client,