Web MIDI: add an unit test to check MidiManager instantiation

media/midi/midi_manager.h

 // 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.
 
 #ifndef MEDIA_MIDI_MIDI_MANAGER_H_
 #define MEDIA_MIDI_MIDI_MANAGER_H_
 
 #include <map>
 #include <set>
 #include <vector>
 
 #include "base/basictypes.h"
+#include "base/memory/ref_counted.h"
 #include "base/synchronization/lock.h"
 #include "base/time/time.h"
 #include "media/base/media_export.h"
 #include "media/midi/midi_port_info.h"
 #include "media/midi/midi_result.h"
 
+namespace base {
+class SingleThreadTaskRunner;
+}  // namespace base
+
 namespace media {
 
 // A MidiManagerClient registers with the MidiManager to receive MIDI data.
 // See MidiManager::RequestAccess() and MidiManager::ReleaseAccess()
 // for details.
 class MEDIA_EXPORT MidiManagerClient {
  public:
   virtual ~MidiManagerClient() {}
 
   // CompleteStartSession() is called when platform dependent preparation is
@@ skipping 14 matching lines @@
   // AccumulateMidiBytesSent() is called to acknowledge when bytes have
   // successfully been sent to the hardware.
   // This happens as a result of the client having previously called
   // MidiManager::DispatchSendMidiData().
   virtual void AccumulateMidiBytesSent(size_t n) = 0;
 };
 
 // Manages access to all MIDI hardware.
 class MEDIA_EXPORT MidiManager {
  public:
+  // The constructor and the destructor will be called on the CrBrowserMain
+  // thread.
   static MidiManager* Create();
 
   MidiManager();
   virtual ~MidiManager();
 
   // A client calls StartSession() to receive and send MIDI data.
   // If the session is ready to start, the MIDI system is lazily initialized
   // and the client is registered to receive MIDI data.
   // CompleteStartSession() is called with MIDI_OK if the session is started.
   // Otherwise CompleteStartSession() is called with proper MidiResult code.
+  // StartSession() and EndSession() can be called on the Chrome_IOThread.
+  // CompleteStartSession() will be invoked on the same Chrome_IOThread.
   void StartSession(MidiManagerClient* client, int client_id);
 
   // A client calls EndSession() to stop receiving MIDI data.
   void EndSession(MidiManagerClient* client);
 
   // DispatchSendMidiData() is called when MIDI data should be sent to the MIDI
   // system.
   // This method is supposed to return immediately and should not block.
   // |port_index| represents the specific output port from output_ports().
   // |data| represents a series of bytes encoding one or more MIDI messages.
@@ skipping 12 matching lines @@
   const MidiPortInfoList& input_ports() { return input_ports_; }
 
   // output_ports() is a list of MIDI ports for sending MIDI data.
   // Each individual port in this list can be identified by its
   // integer index into this list.
   const MidiPortInfoList& output_ports() { return output_ports_; }
 
  protected:
   friend class MidiManagerUsb;
 
-  // Initializes the platform dependent MIDI system. It will call
-  // CompleteInitialization() asynchronously when initialization is finished.
-  // |result| of CompleteInitialization() will be MIDI_OK on success.
-  // MidiManager has a default implementation that calls
-  // CompleteInitialization() with MIDI_NOT_SUPPORTED.
+  // Initializes the platform dependent MIDI system. MidiManager class has a
+  // default implementation that synchronously calls CompleteInitialization()
+  // with MIDI_NOT_SUPPORTED on the caller thread. A derived class for a
+  // specific platform should override this method correctly.
+  // This method is called on Chrome_IOThread thread inside StartSession().
+  // Platform dependent initialization can be processed synchronously or
+  // asynchronously. When the initialization is completed,
+  // CompleteInitialization() should be called with |result|.
+  // |result| should be MIDI_OK on success, otherwise a proper MidiResult.
   virtual void StartInitialization();
 
   // Called from a platform dependent implementation of StartInitialization().
-  // It will distribute |result| to MIDIManagerClient objects in
+  // It invokes CompleteInitializationInternal() on the thread that calls
+  // StartSession() and distributes |result| to MIDIManagerClient objects in
   // |pending_clients_|.
   void CompleteInitialization(MidiResult result);
 
   void AddInputPort(const MidiPortInfo& info);
   void AddOutputPort(const MidiPortInfo& info);
 
   // Dispatches to all clients.
   // TODO(toyoshim): Fix the mac implementation to use
   // |ReceiveMidiData(..., base::TimeTicks)|.
   void ReceiveMidiData(uint32 port_index,
                        const uint8* data,
                        size_t length,
                        double timestamp);
 
   void ReceiveMidiData(uint32 port_index,
                        const uint8* data,
                        size_t length,
                        base::TimeTicks time) {
     ReceiveMidiData(port_index, data, length,
                     (time - base::TimeTicks()).InSecondsF());
   }
 
-  bool initialized_;
-  MidiResult result_;
+  size_t get_clients_size_for_testing() { return clients_.size(); }

[yukawa, 2014/05/06 02:46:02]

nit: size_t get_clients_size_for_testing() const { ...

[Takashi Toyoshima, 2014/05/06 11:11:52]

Done.

+  size_t get_pending_clients_size_for_testing() {

[yukawa, 2014/05/06 02:46:02]

nit: size_t get_pending_clients_size_for_testing() const {

[Takashi Toyoshima, 2014/05/06 11:11:52]

Done.

+    return pending_clients_.size();
+  }
+
+ private:
+  void CompleteInitializationInternal(MidiResult result);
 
   // Keeps track of all clients who wish to receive MIDI data.
   typedef std::set<MidiManagerClient*> ClientList;
   ClientList clients_;
 
   // Keeps track of all clients who are waiting for CompleteStartSession().
   typedef std::map<int, MidiManagerClient*> PendingClientMap;
   PendingClientMap pending_clients_;
 
-  // Protects access to our clients, |clients_| and |pending_clients_|.
-  base::Lock clients_lock_;
+  // Keeps a SingleThreadTaskRunner of the thread that calls StartSession in
+  // order to invoke CompleteStartSession() on the thread.
+  scoped_refptr<base::SingleThreadTaskRunner> session_thread_runner_;
+
+  // Keeps true if platform dependent initialization is already completed.
+  bool initialized_;
+
+  // Keeps the platform dependent initialization result if initialization is
+  // completed. Otherwise keeps MIDI_NOT_SUPPORTED.
+  MidiResult result_;
+
+  // Protects access to |clients_|, |pending_clients_|, |initialized_|, and
+  // |result_|.
+  base::Lock lock_;
 
   MidiPortInfoList input_ports_;
   MidiPortInfoList output_ports_;
 
- private:
   DISALLOW_COPY_AND_ASSIGN(MidiManager);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_MIDI_MIDI_MANAGER_H_