Adds plumbing for QUIC early connection migration. No behavior change.

net/quic/quic_connection_test.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/quic/quic_connection.h"
 
 #include <ostream>
 
 #include "base/bind.h"
 #include "base/macros.h"
@@ skipping 3355 matching lines @@
     InSequence s;
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, first_packet_size, _));
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, second_packet_size, _));
   }
   connection_.GetRetransmissionAlarm()->Fire();
 
   // Advance again and expect the packets to be sent again in the same order.
   clock_.AdvanceTime(QuicTime::Delta::FromSeconds(20));
   {
     InSequence s;
+    EXPECT_CALL(visitor_, OnPathDegrading());
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, first_packet_size, _));
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, second_packet_size, _));
   }
   connection_.GetRetransmissionAlarm()->Fire();
 }
 
 TEST_P(QuicConnectionTest, SetRTOAfterWritingToSocket) {
   BlockOnNextWrite();
   connection_.SendStreamDataWithString(1, "foo", 0, !kFin, nullptr);
   // Make sure that RTO is not started when the packet is queued.
@@ skipping 2117 matching lines @@
   EXPECT_TRUE(connection_.connected());
   EXPECT_FALSE(QuicConnectionPeer::IsMultipathEnabled(&connection_));
   peer_creator_.SetCurrentPath(/*path_id=*/1u, 1u, 10u);
   QuicStreamFrame stream_frame(1u, false, 0u, StringPiece());
   EXPECT_DFATAL(ProcessFramePacket(QuicFrame(&stream_frame)),
                 "Received a packet with multipath flag on when multipath is "
                 "not enabled.");
   EXPECT_FALSE(connection_.connected());
 }
 
+TEST_P(QuicConnectionTest, OnPathDegrading) {
+  QuicByteCount packet_size;
+  const size_t kMinTimeoutsBeforePathDegrading = 2;
+
+  EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _))
+      .WillOnce(DoAll(SaveArg<3>(&packet_size), Return(true)));
+  connection_.SendStreamDataWithString(3, "packet", 0, !kFin, nullptr);
+  for (size_t i = 1; i < kMinTimeoutsBeforePathDegrading; ++i) {
+    clock_.AdvanceTime(QuicTime::Delta::FromSeconds(10 * i));
+    EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, packet_size, _));
+    connection_.GetRetransmissionAlarm()->Fire();
+  }
+  // Next RTO should cause OnPathDegrading to be called before the
+  // retransmission is sent out.
+  clock_.AdvanceTime(
+      QuicTime::Delta::FromSeconds(kMinTimeoutsBeforePathDegrading * 10));
+  {
+    InSequence s;
+    EXPECT_CALL(visitor_, OnPathDegrading());
+    EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, packet_size, _));
+  }
+  connection_.GetRetransmissionAlarm()->Fire();
+}
+
 }  // namespace
 }  // namespace test
 }  // namespace net