Fix MDnsClient's cache entry cleanup logic.

net/dns/mdns_client_impl.h

Index: net/dns/mdns_client_impl.h
diff --git a/net/dns/mdns_client_impl.h b/net/dns/mdns_client_impl.h
index 4ed85f24ac7404b1dafc7411a12ef171f0e49090..f5e7e144d526622c1470910160f5ed3885a545c7 100644
--- a/net/dns/mdns_client_impl.h
+++ b/net/dns/mdns_client_impl.h
@@ -6,6 +6,7 @@
 #define NET_DNS_MDNS_CLIENT_IMPL_H_
 
 #include <map>
+#include <queue>
 #include <string>
 #include <utility>
 #include <vector>
@@ -21,11 +22,16 @@
 #include "net/udp/udp_server_socket.h"
 #include "net/udp/udp_socket.h"
 
+namespace base {
+class Clock;
+class Timer;
+}  // namespace base
+
 namespace net {
 
 class MDnsSocketFactoryImpl : public MDnsSocketFactory {
  public:
-  MDnsSocketFactoryImpl() {};
+  MDnsSocketFactoryImpl() {}
   ~MDnsSocketFactoryImpl() override{};
 
   void CreateSockets(ScopedVector<DatagramServerSocket>* sockets) override;
@@ -132,6 +138,8 @@ class NET_EXPORT_PRIVATE MDnsClientImpl : public MDnsClient {
     void OnConnectionError(int error) override;
 
    private:
+    FRIEND_TEST_ALL_PREFIXES(MDnsTest, CacheCleanupWithShortTTL);
+
     typedef std::pair<std::string, uint16> ListenerKey;
     typedef std::map<ListenerKey, ObserverList<MDnsListenerImpl>* >
     ListenerMap;
@@ -155,11 +163,16 @@ class NET_EXPORT_PRIVATE MDnsClientImpl : public MDnsClient {
     // list if is empty.
     void CleanupObserverList(const ListenerKey& key);
 
+    void set_cleanup_timer_for_test(scoped_ptr<base::Timer> timer);
+
+    void set_clock_for_test(scoped_ptr<base::Clock> clock);
+
     ListenerMap listeners_;
 
     MDnsCache cache_;
 
-    base::CancelableClosure cleanup_callback_;
+    scoped_ptr<base::Clock> clock_;
+    scoped_ptr<base::Timer> cleanup_timer_;
     base::Time scheduled_cleanup_;
 
     scoped_ptr<MDnsConnection> connection_;