Change QuicConnection's ScopedPacketBundler to use SEND_QUEUED_ACK instead of NO_ACK, to ensure a q…

net/quic/quic_connection.h

Index: net/quic/quic_connection.h
diff --git a/net/quic/quic_connection.h b/net/quic/quic_connection.h
index bf4e85cb2e489c071b22a20aae1c6880e81488a9..8de330bb81acd000d8f6f01eaeab2d5e65e81fd7 100644
--- a/net/quic/quic_connection.h
+++ b/net/quic/quic_connection.h
@@ -296,9 +296,12 @@ class NET_EXPORT_PRIVATE QuicConnection
       public QuicSentPacketManager::NetworkChangeVisitor {
  public:
   enum AckBundling {
-    NO_ACK = 0,
-    SEND_ACK = 1,
-    BUNDLE_PENDING_ACK = 2,
+    // Send an ack if it's already queued in the connection.
+    SEND_ACK_IF_QUEUED,
+    // Always send an ack.
+    SEND_ACK,
+    // Bundle an ack with outgoing data.
+    SEND_ACK_IF_PENDING,
   };
 
   enum AckMode { TCP_ACKING, ACK_DECIMATION, ACK_DECIMATION_WITH_REORDERING };
@@ -613,6 +616,8 @@ class NET_EXPORT_PRIVATE QuicConnection
     ~ScopedPacketBundler();
 
    private:
+    bool ShouldSendAck(AckBundling ack_mode) const;
+
     QuicConnection* connection_;
     bool already_in_batch_mode_;
   };
@@ -657,6 +662,8 @@ class NET_EXPORT_PRIVATE QuicConnection
     return termination_packets_.get();
   }
 
+  bool ack_queued() const { return ack_queued_; }
+
   bool ack_frame_updated() const;
 
   QuicConnectionHelperInterface* helper() { return helper_; }
@@ -847,7 +854,7 @@ class NET_EXPORT_PRIVATE QuicConnection
   // True if the last packet has gotten far enough in the framer to be
   // decrypted.
   bool last_packet_decrypted_;
-  QuicByteCount last_size_;   // Size of the last received packet.
+  QuicByteCount last_size_;  // Size of the last received packet.
   // TODO(rch): remove this when b/27221014 is fixed.
   const char* current_packet_data_;  // UDP payload of packet currently being
                                      // parsed or nullptr.