Web MIDI: MIDI input messages may be lost or cause a crash on OS X

media/midi/midi_manager_mac.cc

 // Copyright (c) 2013 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 "media/midi/midi_manager_mac.h"
 
 #include <algorithm>
 #include <string>
 
 #include "base/bind.h"
@@ skipping 269 matching lines @@
 
   // Lookup the port index based on the source.
   SourceMap::iterator j = source_map_.find(source);
   if (j == source_map_.end())
     return;
   // This is safe since MidiManagerMac does not remove any existing
   // MIDIEndpointRef, and the order is saved.
   uint32 port_index = source_map_[source];
 
   // Go through each packet and process separately.
+  const MIDIPacket* packet = &packet_list->packet[0];
   for (size_t i = 0; i < packet_list->numPackets; i++) {
     // Each packet contains MIDI data for one or more messages (like note-on).
-    const MIDIPacket &packet = packet_list->packet[i];
-    double timestamp_seconds = MIDITimeStampToSeconds(packet.timeStamp);
+    double timestamp_seconds = MIDITimeStampToSeconds(packet->timeStamp);
 
     ReceiveMidiData(
         port_index,
-        packet.data,
-        packet.length,
+        packet->data,
+        packet->length,
         timestamp_seconds);
+
+    packet = MIDIPacketNext(packet);
   }
 }
 
 void MidiManagerMac::SendMidiData(MidiManagerClient* client,
                                   uint32 port_index,
                                   const std::vector<uint8>& data,
                                   double timestamp) {
   DCHECK(client_thread_.message_loop_proxy()->BelongsToCurrentThread());
 
   // System Exclusive has already been filtered.
@@ skipping 15 matching lines @@
 
   MIDISend(coremidi_output_, destination, packet_list_);
 
   // Re-initialize for next time.
   midi_packet_ = MIDIPacketListInit(packet_list_);
 
   client->AccumulateMidiBytesSent(data.size());
 }
 
 }  // namespace media