Code: void MidiManagerUsb::DispatchSendMidiData(MidiManagerClient* client,
                                           uint32_t port_index,
                                           const std::vector<uint8>& data,
                                           double timestamp) {
  DCHECK_LT(port_index, output_streams_.size());
   output_streams_[port_index]->Send(data);
   client->AccumulateMidiBytesSent(data.size());
 }

Vulnerability Type: DoS Overflow 
CWE ID: CWE-119
Summary: Array index error in the MidiManagerUsb::DispatchSendMidiData function in media/midi/midi_manager_usb.cc in Google Chrome before 41.0.2272.76 allows remote attackers to cause a denial of service or possibly have unspecified other impact by leveraging renderer access to provide an invalid port index that triggers an out-of-bounds write operation, a different vulnerability than CVE-2015-1212.
Commit Message: MidiManagerUsb should not trust indices provided by renderer.

MidiManagerUsb::DispatchSendMidiData takes |port_index| parameter. As it is
provided by a renderer possibly under the control of an attacker, we must
validate the given index before using it.

BUG=456516

Review URL: https://codereview.chromium.org/907793002

Cr-Commit-Position: refs/heads/master@{#315303}