Remove an unneeded hash_set from QuicAckNotifierManager.

net/quic/quic_ack_notifier_manager.cc

Index: net/quic/quic_ack_notifier_manager.cc
diff --git a/net/quic/quic_ack_notifier_manager.cc b/net/quic/quic_ack_notifier_manager.cc
index 613ba4c01ab3739a10fb990ab03646df9bd53ac6..357c5469133e19d50abc9fe4133a159143c3609a 100644
--- a/net/quic/quic_ack_notifier_manager.cc
+++ b/net/quic/quic_ack_notifier_manager.cc
@@ -20,7 +20,13 @@ namespace net {
 AckNotifierManager::AckNotifierManager() {}
 
 AckNotifierManager::~AckNotifierManager() {
-  STLDeleteElements(&ack_notifiers_);
+  for (const auto& pair : ack_notifier_map_) {
+    for (QuicAckNotifier* notifier : pair.second) {
+      if (notifier->OnPacketAbandoned()) {
+        delete notifier;
+      }
+    }
+  }
 }
 
 void AckNotifierManager::OnPacketAcked(QuicPacketSequenceNumber sequence_number,
@@ -39,9 +45,8 @@ void AckNotifierManager::OnPacketAcked(QuicPacketSequenceNumber sequence_number,
     ack_notifier->OnAck(sequence_number, delta_largest_observed);
 
     // If this has resulted in an empty AckNotifer, erase it.
-    if (ack_notifier->IsEmpty()) {
+    if (!ack_notifier->HasUnackedPackets()) {
       delete ack_notifier;
-      ack_notifiers_.erase(ack_notifier);
     }
   }
 
@@ -86,9 +91,6 @@ void AckNotifierManager::OnSerializedPacket(
       // Update the mapping in the other direction, from sequence number to
       // AckNotifier.
       ack_notifier_map_[serialized_packet.sequence_number].push_back(notifier);
-
-      // Take ownership of the AckNotifier.
-      ack_notifiers_.insert(notifier);
     }
   } else {
     // AckNotifiers can only be attached to retransmittable frames.
@@ -111,9 +113,6 @@ void AckNotifierManager::OnSerializedPacket(
       // Update the mapping in the other direction, from sequence number to
       // AckNotifier.
       ack_notifier_map_[serialized_packet.sequence_number].push_back(notifier);
-
-      // Take ownership of the AckNotifier.
-      ack_notifiers_.insert(notifier);
     }
   }
 }