Web MIDI: add dynamic MidiManager instantiation support for Linux

media/midi/midi_manager_alsa.h

 // 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.
 
 #ifndef MEDIA_MIDI_MIDI_MANAGER_ALSA_H_
 #define MEDIA_MIDI_MIDI_MANAGER_ALSA_H_
 
 #include <alsa/asoundlib.h>
 #include <stdint.h>
 
@@ skipping 13 matching lines @@
 #include "media/midi/midi_manager.h"
 
 namespace base {
 class ThreadChecker;
 }
 
 namespace midi {
 
 class MIDI_EXPORT MidiManagerAlsa final : public MidiManager {
  public:
-  MidiManagerAlsa();
+  explicit MidiManagerAlsa(MidiService* service);
   ~MidiManagerAlsa() override;
 
   // MidiManager implementation.
   void StartInitialization() override;
   void Finalize() override;
   void DispatchSendMidiData(MidiManagerClient* client,
                             uint32_t port_index,
                             const std::vector<uint8_t>& data,
                             double timestamp) override;
 
@@ skipping 321 matching lines @@
     };
   };
 
   using SourceMap = base::hash_map<int, uint32_t>;
   using OutPortMap = base::hash_map<uint32_t, int>;
   using ScopedSndSeqPtr = std::unique_ptr<snd_seq_t, SndSeqDeleter>;
   using ScopedSndMidiEventPtr =
       std::unique_ptr<snd_midi_event_t, SndMidiEventDeleter>;
 
   // An internal callback that runs on MidiSendThread.
-  void SendMidiData(uint32_t port_index, const std::vector<uint8_t>& data);
+  void SendMidiData(int instance_id,
+                    MidiManagerClient* client,
+                    uint32_t port_index,
+                    const std::vector<uint8_t>& data);
 
-  void ScheduleEventLoop();
-  void EventLoop();
+  void EventLoop(int instance_id);
   void ProcessSingleEvent(snd_seq_event_t* event, double timestamp);
   void ProcessClientStartEvent(int client_id);
   void ProcessPortStartEvent(const snd_seq_addr_t& addr);
   void ProcessClientExitEvent(const snd_seq_addr_t& addr);
   void ProcessPortExitEvent(const snd_seq_addr_t& addr);
   void ProcessUdevEvent(udev_device* dev);
   void AddCard(udev_device* dev);
   void RemoveCard(int number);
 
   // Updates port_state_ and Web MIDI state from alsa_seq_state_.
@@ skipping 23 matching lines @@
 
   // Mapping from card to devices.
   AlsaCardMap alsa_cards_;
 
   // This is the current count of midi devices across all cards we know
   // about. When this number matches card_client_count_ in AlsaSeqState,
   // we are safe to generate MIDIConnectionEvents. Otherwise we need to
   // wait for our information from ALSA and udev to get back in sync.
   int alsa_card_midi_count_ = 0;
 
-  base::Lock shutdown_lock_;            // guards event_thread_shutdown_
-  bool event_thread_shutdown_ = false;  // guarded by shutdown_lock_
-
   // This lock is needed to ensure that members destroyed in Finalize
   // will be visibly destroyed before the destructor is run in the
   // other thread. Otherwise, the same objects may have their destructors
   // run multiple times in different threads.
   base::Lock lazy_init_member_lock_;  // guards members below
 
   // Members initialized in StartInitialization() are below.
   // Make sure to destroy these in Finalize()!
   std::unique_ptr<base::ThreadChecker> initialization_thread_checker_;
 
   // ALSA seq handles and ids.
   ScopedSndSeqPtr in_client_;
   int in_client_id_;
   ScopedSndSeqPtr out_client_;
   int out_client_id_;
   int in_port_id_;
 
   // ALSA event -> MIDI coder.
   ScopedSndMidiEventPtr decoder_;
 
   // udev, for querying hardware devices.
   device::ScopedUdevPtr udev_;
   device::ScopedUdevMonitorPtr udev_monitor_;
 
-  // Threads for sending and receiving. These are initialized in the
-  // constructor, but are started at the end of StartInitialization.
-  base::Thread event_thread_;
-  base::Thread send_thread_;
+  int instance_id_;
 
   DISALLOW_COPY_AND_ASSIGN(MidiManagerAlsa);
 };
 
 }  // namespace midi
 
 #endif  // MEDIA_MIDI_MIDI_MANAGER_ALSA_H_