DNS: Let requests specify a callback for future cache hits

net/dns/host_resolver_impl.h

Index: net/dns/host_resolver_impl.h
diff --git a/net/dns/host_resolver_impl.h b/net/dns/host_resolver_impl.h
index 54de1c8e4fa947fb67bdd4b6f695145a9d7b85de..2f2cca1e17369d6936edb99104fbf8f66a51a42b 100644
--- a/net/dns/host_resolver_impl.h
+++ b/net/dns/host_resolver_impl.h
@@ -299,12 +299,19 @@ class NET_EXPORT HostResolverImpl
   // and resulted in |net_error|.
   void OnDnsTaskResolve(int net_error);
 
-  void SchedulePersist();
-  void DoPersist();
+  void OnCacheEntryEvicted(const HostCache::Key& key,
+                           const HostCache::Entry& entry);
+  void ClearCacheHitCallbacks(const HostCache::Key& key);
+  void MaybeAddCacheHitCallback(const HostCache::Key& key,
+                                const RequestInfo& info);
+  void RunCacheHitCallbacks(const HostCache::Key& key, const RequestInfo& info);
 
   void ApplyPersistentData(std::unique_ptr<const base::Value>);
   std::unique_ptr<const base::Value> GetPersistentData();
 
+  void SchedulePersist();
+  void DoPersist();
+
   // Allows the tests to catch slots leaking out of the dispatcher.  One
   // HostResolverImpl::Job could occupy multiple PrioritizedDispatcher job
   // slots.
@@ -361,6 +368,9 @@ class NET_EXPORT HostResolverImpl
   // tasks, but can be overridden for tests.
   scoped_refptr<base::TaskRunner> worker_task_runner_;
 
+  std::map<const HostCache::Key, std::vector<RequestInfo::CacheHitCallback>>
+      cache_hit_callbacks_;
+
   bool persist_initialized_;
   PersistCallback persist_callback_;
   base::OneShotTimer persist_timer_;