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

content/browser/renderer_host/media/midi_host.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 CONTENT_BROWSER_RENDERER_HOST_MEDIA_MIDI_HOST_H_
 #define CONTENT_BROWSER_RENDERER_HOST_MEDIA_MIDI_HOST_H_
 
+#include <vector>
+
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "content/common/content_export.h"
 #include "content/public/browser/browser_message_filter.h"
 #include "content/public/browser/browser_thread.h"
 #include "media/midi/midi_manager.h"
 
 namespace media {
 class MIDIManager;
 }
@@ skipping 18 matching lines @@
       int port_index,
       const uint8* data,
       size_t length,
       double timestamp) OVERRIDE;
   virtual void AccumulateMIDIBytesSent(size_t n) OVERRIDE;
 
   // Start session to access MIDI hardware.
   void OnStartSession(int client_id);
 
   // Data to be sent to a MIDI output port.
-  void OnSendData(int port,
+  void OnSendData(uint32 port,
                   const std::vector<uint8>& data,
                   double timestamp);
 
  private:
   friend class base::DeleteHelper<MIDIHost>;
   friend class BrowserThread;
 
   virtual ~MIDIHost();
 
   // |midi_manager_| talks to the platform-specific MIDI APIs.
@@ skipping 13 matching lines @@
 
   // Protects access to |sent_bytes_in_flight_|.
   base::Lock in_flight_lock_;
 
   DISALLOW_COPY_AND_ASSIGN(MIDIHost);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_MEDIA_MIDI_HOST_H_