Don't detect a new frame if a previous packet is used in a previous frame.

webrtc/test/fuzzers/packet_buffer_fuzzer.cc

+/*
+ *  Copyright (c) 2017 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.
+ */
+
+#include "webrtc/modules/video_coding/packet_buffer.h"
+#include "webrtc/system_wrappers/include/clock.h"
+
+namespace webrtc {
+
+namespace {
+class NullCallback : public video_coding::OnReceivedFrameCallback {
+  void OnReceivedFrame(std::unique_ptr<video_coding::RtpFrameObject> frame) {}
+};
+}  // namespace
+
+void FuzzOneInput(const uint8_t* data, size_t size) {
+  // Two bytes for the sequence number,
+  // one byte for |is_first_packet_in_frame| and |markerBit|.
+  constexpr size_t kMinDataNeeded = 3;
+  if (size < kMinDataNeeded) {
+    return;
+  }
+
+  VCMPacket packet;
+  NullCallback callback;
+  SimulatedClock clock(0);
+  rtc::scoped_refptr<video_coding::PacketBuffer> packet_buffer(
+      video_coding::PacketBuffer::Create(&clock, 8, 1024, &callback));
+
+  size_t i = kMinDataNeeded;
+  while (i < size) {
+    memcpy(&packet.seqNum, &data[i - kMinDataNeeded], 2);
+    packet.is_first_packet_in_frame = data[i] & 1;
+    packet.markerBit = data[i] & 2;
+    packet_buffer->InsertPacket(&packet);
+    i += kMinDataNeeded;
+  }
+}
+
+}  // namespace webrtc