Web MIDI: fix multi-threading problem around message buffer handling

media/midi/midi_manager_mac.h

Index: media/midi/midi_manager_mac.h
diff --git a/media/midi/midi_manager_mac.h b/media/midi/midi_manager_mac.h
index ed7b524f5c4d7060de80c0b544ddceb54a8f2e1d..2342571783ea968768d7f2175e1c3b735851411b 100644
--- a/media/midi/midi_manager_mac.h
+++ b/media/midi/midi_manager_mac.h
@@ -8,6 +8,7 @@
 #include <CoreMIDI/MIDIServices.h>
 #include <map>
 #include <string>
+#include <vector>
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
@@ -24,9 +25,8 @@ class MEDIA_EXPORT MIDIManagerMac : public MIDIManager {
   // MIDIManager implementation.
   virtual bool Initialize() OVERRIDE;
   virtual void SendMIDIData(MIDIManagerClient* client,
-                            int port_index,
-                            const uint8* data,
-                            size_t length,
+                            size_t port_index,
+                            const std::vector<uint8>& data,
                             double timestamp) OVERRIDE;
 
  private: