Fix bug 574524: DtlsTransportChannel crashes after SSL closes remotely

webrtc/base/bufferqueue.cc

 /*
  *  Copyright 2015 The WebRTC Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 14 matching lines @@
   for (Buffer* buffer : free_list_) {
     delete buffer;
   }
 }
 
 size_t BufferQueue::size() const {
   CritScope cs(&crit_);
   return queue_.size();
 }
 
+void BufferQueue::Clear() {
+  CritScope cs(&crit_);
+  while (!queue_.empty()) {
+    free_list_.push_back(queue_.front());
+    queue_.pop_front();
+  }
+}
+
 bool BufferQueue::ReadFront(void* buffer, size_t bytes, size_t* bytes_read) {
   CritScope cs(&crit_);
   if (queue_.empty()) {
     return false;
   }
 
   bool was_writable = queue_.size() < capacity_;
   Buffer* packet = queue_.front();
   queue_.pop_front();
 
@@ skipping 30 matching lines @@
     *bytes_written = bytes;
   }
   queue_.push_back(packet);
   if (!was_readable) {
     NotifyReadableForTest();
   }
   return true;
 }
 
 }  // namespace rtc