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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_MEDIA_MIDI_HOST_H_
      6 #define CONTENT_BROWSER_MEDIA_MIDI_HOST_H_
      7 
      8 #include <vector>
      9 
     10 #include "base/gtest_prod_util.h"
     11 #include "base/memory/ref_counted.h"
     12 #include "base/memory/scoped_ptr.h"
     13 #include "base/memory/scoped_vector.h"
     14 #include "content/common/content_export.h"
     15 #include "content/public/browser/browser_message_filter.h"
     16 #include "content/public/browser/browser_thread.h"
     17 #include "media/midi/midi_manager.h"
     18 
     19 namespace media {
     20 class MidiManager;
     21 class MidiMessageQueue;
     22 }
     23 
     24 namespace content {
     25 
     26 class CONTENT_EXPORT MidiHost
     27     : public BrowserMessageFilter,
     28       public media::MidiManagerClient {
     29  public:
     30   // Called from UI thread from the owner of this object.
     31   MidiHost(int renderer_process_id, media::MidiManager* midi_manager);
     32 
     33   // BrowserMessageFilter implementation.
     34   virtual void OnDestruct() const OVERRIDE;
     35   virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;
     36 
     37   // MidiManagerClient implementation.
     38   virtual void CompleteStartSession(int client_id,
     39                                     media::MidiResult result) OVERRIDE;
     40   virtual void ReceiveMidiData(uint32 port,
     41                                const uint8* data,
     42                                size_t length,
     43                                double timestamp) OVERRIDE;
     44   virtual void AccumulateMidiBytesSent(size_t n) OVERRIDE;
     45 
     46   // Start session to access MIDI hardware.
     47   void OnStartSession(int client_id);
     48 
     49   // Data to be sent to a MIDI output port.
     50   void OnSendData(uint32 port,
     51                   const std::vector<uint8>& data,
     52                   double timestamp);
     53 
     54  private:
     55   FRIEND_TEST_ALL_PREFIXES(MidiHostTest, IsValidWebMIDIData);
     56   friend class base::DeleteHelper<MidiHost>;
     57   friend class BrowserThread;
     58 
     59   virtual ~MidiHost();
     60 
     61   // Returns true if |data| fulfills the requirements of MidiOutput.send API
     62   // defined in the WebMIDI spec.
     63   // - |data| must be any number of complete MIDI messages (data abbreviation
     64   //    called "running status" is disallowed).
     65   // - 1-byte MIDI realtime messages can be placed at any position of |data|.
     66   static bool IsValidWebMIDIData(const std::vector<uint8>& data);
     67 
     68   int renderer_process_id_;
     69 
     70   // Represents if the renderer has a permission to send/receive MIDI SysEX
     71   // messages.
     72   bool has_sys_ex_permission_;
     73 
     74   // |midi_manager_| talks to the platform-specific MIDI APIs.
     75   // It can be NULL if the platform (or our current implementation)
     76   // does not support MIDI.  If not supported then a call to
     77   // OnRequestAccess() will always refuse access and a call to
     78   // OnSendData() will do nothing.
     79   media::MidiManager* const midi_manager_;
     80 
     81   // Buffers where data sent from each MIDI input port is stored.
     82   ScopedVector<media::MidiMessageQueue> received_messages_queues_;
     83 
     84   // The number of bytes sent to the platform-specific MIDI sending
     85   // system, but not yet completed.
     86   size_t sent_bytes_in_flight_;
     87 
     88   // The number of bytes successfully sent since the last time
     89   // we've acknowledged back to the renderer.
     90   size_t bytes_sent_since_last_acknowledgement_;
     91 
     92   // Protects access to |sent_bytes_in_flight_|.
     93   base::Lock in_flight_lock_;
     94 
     95   DISALLOW_COPY_AND_ASSIGN(MidiHost);
     96 };
     97 
     98 }  // namespace content
     99 
    100 #endif  // CONTENT_BROWSER_MEDIA_MIDI_HOST_H_
    101