Web MIDI: introduce MidiManager::Shutdown to shutdown gracefully

content/browser/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_MEDIA_MIDI_HOST_H_
 #define CONTENT_BROWSER_MEDIA_MIDI_HOST_H_
 
 #include <vector>
 
 #include "base/gtest_prod_util.h"
@@ skipping 32 matching lines @@
   void AddOutputPort(const media::midi::MidiPortInfo& info) override;
   void SetInputPortState(uint32 port,
                          media::midi::MidiPortState state) override;
   void SetOutputPortState(uint32 port,
                           media::midi::MidiPortState state) override;
   void ReceiveMidiData(uint32 port,
                        const uint8* data,
                        size_t length,
                        double timestamp) override;
   void AccumulateMidiBytesSent(size_t n) override;
+  void Detach() override;
 
   // Start session to access MIDI hardware.
   void OnStartSession();
 
   // Data to be sent to a MIDI output port.
   void OnSendData(uint32 port,
                   const std::vector<uint8>& data,
                   double timestamp);
 
   void OnEndSession();
 
  protected:
   ~MidiHost() override;
 
  private:
   FRIEND_TEST_ALL_PREFIXES(MidiHostTest, IsValidWebMIDIData);
   friend class base::DeleteHelper<MidiHost>;
   friend class BrowserThread;
 
   // Returns true if |data| fulfills the requirements of MidiOutput.send API
-  // defined in the WebMIDI spec.
+  // defined in the Web MIDI spec.
   // - |data| must be any number of complete MIDI messages (data abbreviation
   //    called "running status" is disallowed).
   // - 1-byte MIDI realtime messages can be placed at any position of |data|.
   static bool IsValidWebMIDIData(const std::vector<uint8>& data);
 
   int renderer_process_id_;
 
   // Represents if the renderer has a permission to send/receive MIDI SysEX
   // messages.
   bool has_sys_ex_permission_;
 
   // Represents if a session is requested to start.
   bool is_session_requested_;
 
   // |midi_manager_| talks to the platform-specific MIDI APIs.
   // It can be NULL if the platform (or our current implementation)
   // does not support MIDI.  If not supported then a call to
   // OnRequestAccess() will always refuse access and a call to
   // OnSendData() will do nothing.
-  media::midi::MidiManager* const midi_manager_;
+  media::midi::MidiManager* midi_manager_;
 
   // Buffers where data sent from each MIDI input port is stored.
   ScopedVector<media::midi::MidiMessageQueue> received_messages_queues_;
 
   // Protects access to |received_messages_queues_|;
   base::Lock messages_queues_lock_;
 
   // The number of bytes sent to the platform-specific MIDI sending
   // system, but not yet completed.
   size_t sent_bytes_in_flight_;
@@ skipping 10 matching lines @@
 
   // Protects access to |output_port_count_|.
   base::Lock output_port_count_lock_;
 
   DISALLOW_COPY_AND_ASSIGN(MidiHost);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_MEDIA_MIDI_HOST_H_