Fix to make sure QuicStreamSequencerBuffer release memory in time.

net/quic/core/quic_stream_sequencer_buffer_test.cc

 // Copyright (c) 2015 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/core/quic_stream_sequencer_buffer.h"
 
 #include <algorithm>
 #include <limits>
 #include <map>
 #include <string>
 #include <utility>
@@ skipping 385 matching lines @@
   EXPECT_TRUE(buffer_->HasBytesToRead());
   EXPECT_EQ(2u, helper_->frame_arrival_time_map()->size());
   // Read into a iovec array with total capacity of 120 bytes.
   char dest[120];
   iovec iovecs[3]{iovec{dest, 40}, iovec{dest + 40, 40}, iovec{dest + 80, 40}};
   size_t read = buffer_->Readv(iovecs, 3);
   EXPECT_EQ(100u, read);
   EXPECT_EQ(100u, buffer_->BytesConsumed());
   EXPECT_EQ(source, string(dest, read));
   EXPECT_EQ(1u, helper_->frame_arrival_time_map()->size());
+  if (FLAGS_quic_sequencer_buffer_retire_block_in_time) {
+    // The first block should be released as its data has been read out.
+    EXPECT_EQ(nullptr, helper_->GetBlock(0));
+  }
   EXPECT_TRUE(helper_->CheckBufferInvariants());
 }
 
 TEST_F(QuicStreamSequencerBufferTest, ReadvAcrossBlocks) {
   string source(kBlockSizeBytes + 50, 'a');
   // Write 1st block to full and extand 50 bytes to next block.
   size_t written;
   buffer_->OnStreamData(0, source, clock_.ApproximateNow(), &written,
                         &error_details_);
   EXPECT_EQ(source.size(), helper_->ReadableBytes());
@@ skipping 635 matching lines @@
   EXPECT_LE(bytes_to_buffer_, total_bytes_read_) << "iterations: "
                                                  << iterations;
   EXPECT_LE(bytes_to_buffer_, total_bytes_written_);
 }
 
 }  // anonymous namespace
 
 }  // namespace test
 
 }  // namespace net