Reporting: Add Observer interface to observe cache updates.

net/reporting/reporting_context.cc

Index: net/reporting/reporting_context.cc
diff --git a/net/reporting/reporting_context.cc b/net/reporting/reporting_context.cc
index 79235e63747aa46267fe2848d0194cf9381af841..cc50dc7aef2456a6f7725b8141790ae38724c2fd 100644
--- a/net/reporting/reporting_context.cc
+++ b/net/reporting/reporting_context.cc
@@ -7,6 +7,7 @@
 #include <memory>
 
 #include "base/memory/ptr_util.h"
+#include "base/observer_list.h"
 #include "base/time/clock.h"
 #include "base/time/default_clock.h"
 #include "base/time/default_tick_clock.h"
@@ -17,6 +18,7 @@
 #include "net/reporting/reporting_delegate.h"
 #include "net/reporting/reporting_delivery_agent.h"
 #include "net/reporting/reporting_endpoint_manager.h"
+#include "net/reporting/reporting_observer.h"
 #include "net/reporting/reporting_policy.h"
 
 namespace net {
@@ -50,6 +52,21 @@ std::unique_ptr<ReportingContext> ReportingContext::Create(
 
 ReportingContext::~ReportingContext() {}
 
+void ReportingContext::AddObserver(ReportingObserver* observer) {
+  DCHECK(!observers_.HasObserver(observer));
+  observers_.AddObserver(observer);
+}
+
+void ReportingContext::RemoveObserver(ReportingObserver* observer) {
+  DCHECK(observers_.HasObserver(observer));
+  observers_.RemoveObserver(observer);
+}
+
+void ReportingContext::NotifyCacheUpdated() {
+  for (auto& observer : observers_)
+    observer.OnCacheUpdated();
+}
+
 ReportingContext::ReportingContext(const ReportingPolicy& policy,
                                    std::unique_ptr<ReportingDelegate> delegate,
                                    std::unique_ptr<base::Clock> clock,