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      1 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef CONTENT_BROWSER_RENDERER_HOST_MEDIA_MIDI_HOST_H_
      6 #define CONTENT_BROWSER_RENDERER_HOST_MEDIA_MIDI_HOST_H_
      7 
      8 #include "base/memory/ref_counted.h"
      9 #include "base/memory/scoped_ptr.h"
     10 #include "content/common/content_export.h"
     11 #include "content/public/browser/browser_message_filter.h"
     12 #include "content/public/browser/browser_thread.h"
     13 #include "media/midi/midi_manager.h"
     14 
     15 namespace media {
     16 class MIDIManager;
     17 }
     18 
     19 namespace content {
     20 
     21 class CONTENT_EXPORT MIDIHost
     22     : public BrowserMessageFilter,
     23       public media::MIDIManagerClient {
     24  public:
     25   // Called from UI thread from the owner of this object.
     26   MIDIHost(media::MIDIManager* midi_manager);
     27 
     28   // BrowserMessageFilter implementation.
     29   virtual void OnChannelClosing() OVERRIDE;
     30   virtual void OnDestruct() const OVERRIDE;
     31   virtual bool OnMessageReceived(const IPC::Message& message,
     32                                  bool* message_was_ok) OVERRIDE;
     33 
     34   // MIDIManagerClient implementation.
     35   virtual void ReceiveMIDIData(
     36       int port_index,
     37       const uint8* data,
     38       size_t length,
     39       double timestamp) OVERRIDE;
     40   virtual void AccumulateMIDIBytesSent(size_t n) OVERRIDE;
     41 
     42   // Start session to access MIDI hardware.
     43   void OnStartSession(int client_id);
     44 
     45   // Data to be sent to a MIDI output port.
     46   void OnSendData(int port,
     47                   const std::vector<uint8>& data,
     48                   double timestamp);
     49 
     50  private:
     51   friend class base::DeleteHelper<MIDIHost>;
     52   friend class BrowserThread;
     53 
     54   virtual ~MIDIHost();
     55 
     56   // |midi_manager_| talks to the platform-specific MIDI APIs.
     57   // It can be NULL if the platform (or our current implementation)
     58   // does not support MIDI.  If not supported then a call to
     59   // OnRequestAccess() will always refuse access and a call to
     60   // OnSendData() will do nothing.
     61   media::MIDIManager* const midi_manager_;
     62 
     63   // The number of bytes sent to the platform-specific MIDI sending
     64   // system, but not yet completed.
     65   size_t sent_bytes_in_flight_;
     66 
     67   // The number of bytes successfully sent since the last time
     68   // we've acknowledged back to the renderer.
     69   size_t bytes_sent_since_last_acknowledgement_;
     70 
     71   // Protects access to |sent_bytes_in_flight_|.
     72   base::Lock in_flight_lock_;
     73 
     74   DISALLOW_COPY_AND_ASSIGN(MIDIHost);
     75 };
     76 
     77 }  // namespace content
     78 
     79 #endif  // CONTENT_BROWSER_RENDERER_HOST_MEDIA_MIDI_HOST_H_
     80