[WebMIDI] MIDIManager::create should return non-null object.

media/midi/midi_manager.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 "media/midi/midi_manager.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 
 namespace media {
 
 #if !defined(OS_MACOSX) && !defined(OS_WIN)
+namespace {
+
+class NullMIDIManager : public MIDIManager {

[Takashi Toyoshima, 2013/12/19 07:58:24]

How about just adding default implementations of Initialize(), and
DispatchSendMIDIDate() on MIDIManager class directly in midi_manager.h? Also
NOTREACHED() is needed inside DispatchSendMIDIData().

[yhirano, 2013/12/19 08:21:54]

Done.

+ public:
+  virtual ~NullMIDIManager();
+  virtual void DispatchSendMIDIData(MIDIManagerClient* client,
+                                    uint32 port_index,
+                                    const std::vector<uint8>& data,
+                                    double timestamp) OVERRIDE;
+  virtual bool Initialize() OVERRIDE;
+};
+
+NullMIDIManager::~NullMIDIManager() {}
+
+void NullMIDIManager::DispatchSendMIDIData(MIDIManagerClient* client,
+                                           uint32 port_index,
+                                           const std::vector<uint8>& data,
+                                           double timestamp) {}
+
+bool NullMIDIManager::Initialize() {
+  return false;
+}
+
+}  // namespace
+
 // TODO(crogers): implement MIDIManager for other platforms.
 MIDIManager* MIDIManager::Create() {
-  return NULL;
+  return new NullMIDIManager;
 }
 #endif
 
 MIDIManager::MIDIManager()
     : initialized_(false) {
 }
 
 MIDIManager::~MIDIManager() {
 }
 
@@ skipping 30 matching lines @@
     const uint8* data,
     size_t length,
     double timestamp) {
   base::AutoLock auto_lock(clients_lock_);
 
   for (ClientList::iterator i = clients_.begin(); i != clients_.end(); ++i)
     (*i)->ReceiveMIDIData(port_index, data, length, timestamp);
 }
 
 }  // namespace media