MidiManagerUsb should not trust indices provided by renderer.

media/midi/midi_manager_usb.cc

 // Copyright 2014 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_usb.h"
 
 #include "base/callback.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop/message_loop.h"
@@ skipping 25 matching lines @@
   device_factory_->EnumerateDevices(
       this,
       base::Bind(&MidiManagerUsb::OnEnumerateDevicesDone,
                  base::Unretained(this)));
 }
 
 void MidiManagerUsb::DispatchSendMidiData(MidiManagerClient* client,
                                           uint32_t port_index,
                                           const std::vector<uint8>& data,
                                           double timestamp) {
-  DCHECK_LT(port_index, output_streams_.size());
+  if (port_index >= output_streams_.size()) {
+    // |port_index| is provided by a renderer so we can't believe that it is
+    // in the valid range.
+    // TODO(toyoshim): Move this check to MidiHost and kill the renderer when
+    // it fails.
+    return;
+  }
   output_streams_[port_index]->Send(data);
   client->AccumulateMidiBytesSent(data.size());
 }
 
 void MidiManagerUsb::ReceiveUsbMidiData(UsbMidiDevice* device,
                                         int endpoint_number,
                                         const uint8* data,
                                         size_t size,
                                         base::TimeTicks time) {
   if (!input_stream_)
@@ skipping 57 matching lines @@
                                      static_cast<long>(j));
         AddInputPort(port);
       }
     }
     input_stream_.reset(new UsbMidiInputStream(input_jacks, this));
   }
   initialize_callback_.Run(MIDI_OK);
 }
 
 }  // namespace media