Web MIDI: distributes MIDIPort information asynchronously

content/browser/media/midi_host.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 "content/browser/media/midi_host.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/debug/trace_event.h"
 #include "base/process/process.h"
@@ skipping 107 matching lines @@
   midi_manager_->DispatchSendMidiData(this, port, data, timestamp);
 }
 
 void MidiHost::OnEndSession() {
   is_session_requested_ = false;
   midi_manager_->EndSession(this);
 }
 
 void MidiHost::CompleteStartSession(media::MidiResult result) {
   DCHECK(is_session_requested_);
-  MidiPortInfoList input_ports;
-  MidiPortInfoList output_ports;
-
   if (result == media::MIDI_OK) {
-    input_ports = midi_manager_->input_ports();
-    output_ports = midi_manager_->output_ports();
-    received_messages_queues_.clear();
-    received_messages_queues_.resize(input_ports.size());
     // ChildSecurityPolicy is set just before OnStartSession by
     // MidiDispatcherHost. So we can safely cache the policy.
     has_sys_ex_permission_ = ChildProcessSecurityPolicyImpl::GetInstance()->
         CanSendMidiSysExMessage(renderer_process_id_);
   }
+  Send(new MidiMsg_SessionStarted(result));
+}
 
-  Send(new MidiMsg_SessionStarted(result,
-                                  input_ports,
-                                  output_ports));
+void MidiHost::AddInputPort(const media::MidiPortInfo& info) {
+  base::AutoLock auto_lock(messages_queues_lock_);
+  // MidiMessageQueue is created later in ReceiveMidiData().
+  received_messages_queues_.push_back(nullptr);
+  Send(new MidiMsg_AddInputPort(info));
+}
+
+void MidiHost::AddOutputPort(const media::MidiPortInfo& info) {
+  Send(new MidiMsg_AddOutputPort(info));
 }
 
 void MidiHost::ReceiveMidiData(
     uint32 port,
     const uint8* data,
     size_t length,
     double timestamp) {
   TRACE_EVENT0("midi", "MidiHost::ReceiveMidiData");
 
+  base::AutoLock auto_lock(messages_queues_lock_);
   if (received_messages_queues_.size() <= port)
     return;
 
   // Lazy initialization
-  if (received_messages_queues_[port] == NULL)
+  if (received_messages_queues_[port] == nullptr)
     received_messages_queues_[port] = new media::MidiMessageQueue(true);
 
   received_messages_queues_[port]->Add(data, length);
   std::vector<uint8> message;
   while (true) {
     received_messages_queues_[port]->Get(&message);
     if (message.empty())
       break;
 
     // MIDI devices may send a system exclusive messages even if the renderer
@@ skipping 53 matching lines @@
     }
     waiting_data_length = media::GetMidiMessageLength(current);
     if (waiting_data_length == 0)
       return false;  // Error: |current| should have been a valid status byte.
     --waiting_data_length;  // Found status byte
   }
   return waiting_data_length == 0 && !in_sysex;
 }
 
 }  // namespace content