Fix a type casting bug in quic stream sequencer buffer.

net/quic/stream_sequencer_buffer.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/stream_sequencer_buffer.h"
 
 #include "base/logging.h"
 #include "net/quic/quic_bug_tracker.h"
 
 using std::min;
@@ skipping 148 matching lines @@
   } else if (gap_with_new_data_written->begin_offset < start_offset &&
              gap_with_new_data_written->end_offset ==
                  start_offset + bytes_written) {
     // New data has been written into the right part of the buffer.
     gap_with_new_data_written->end_offset = start_offset;
   } else if (gap_with_new_data_written->begin_offset < start_offset &&
              gap_with_new_data_written->end_offset >
                  start_offset + bytes_written) {
     // New data has been written into the middle of the buffer.
     auto current = gap_with_new_data_written++;
-    size_t current_end = current->end_offset;
+    QuicStreamOffset current_end = current->end_offset;
     current->end_offset = start_offset;
     gaps_.insert(gap_with_new_data_written,
                  Gap(start_offset + bytes_written, current_end));
   } else if (gap_with_new_data_written->begin_offset == start_offset &&
              gap_with_new_data_written->end_offset ==
                  start_offset + bytes_written) {
     // This gap has been filled with new data. So it's no longer a gap.
     gaps_.erase(gap_with_new_data_written);
   }
 }
@@ skipping 264 matching lines @@
           offset, FrameInfo(erased.first + erased.second.length - offset,
                             erased.second.timestamp));
       DVLOG(1) << "Inserted FrameInfo with offset: " << updated.first
                << " and length: " << updated.second.length;
       frame_arrival_time_map_.insert(updated);
     }
   }
 }
 
 }  //  namespace net