Implementation of 'AudioContext.getOutputTimestamp' method

media/audio/audio_device_thread.h

 // Copyright (c) 2012 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 MEDIA_AUDIO_AUDIO_DEVICE_THREAD_H_
 #define MEDIA_AUDIO_AUDIO_DEVICE_THREAD_H_
 
 #include <stdint.h>
 
 #include "base/macros.h"
 #include "base/memory/shared_memory.h"
 #include "base/sync_socket.h"
 #include "base/threading/platform_thread.h"
 #include "base/threading/thread_checker.h"
+#include "media/audio/audio_io.h"
 #include "media/base/audio_parameters.h"
 #include "media/base/media_export.h"
 
 namespace media {
+struct AudioTimestamp;
 
 // Data transfer between browser and render process uses a combination
 // of sync sockets and shared memory. To read from the socket and render
 // data, we use a worker thread, a.k.a. the AudioDeviceThread, which reads
 // data from the browser via the socket and fills the shared memory from the
 // audio thread via the AudioDeviceThread::Callback interface/class.
 class MEDIA_EXPORT AudioDeviceThread : public base::PlatformThread::Delegate {
  public:
   // This is the callback interface/base class that Audio[Output|Input]Device
   // implements to render input/output data. The callbacks run on the
   // thread owned by AudioDeviceThread.
   class Callback {
    public:
     Callback(const AudioParameters& audio_parameters,
              base::SharedMemoryHandle memory,
              int memory_length,
              int total_segments);
 
     // One time initialization for the callback object on the audio thread.
     void InitializeOnAudioThread();
 
     // Derived implementations must call shared_memory_.Map appropriately
     // before Process can be called.
     virtual void MapSharedMemory() = 0;
 
     // Called whenever we receive notifications about pending input data.
-    virtual void Process(uint32_t pending_data) = 0;
+    // It also provides the current audio stream timestamp on the device.
+    virtual void Process(uint32_t pending_data,
+                         const AudioTimestamp& timestamp) = 0;
 
    protected:
     virtual ~Callback();
 
     // Protected so that derived classes can access directly.
     // The variables are 'const' since values are calculated/set in the
     // constructor and must never change.
     const AudioParameters audio_parameters_;
 
     base::SharedMemory shared_memory_;
@@ skipping 12 matching lines @@
 
   // Creates and automatically starts the audio thread.
   AudioDeviceThread(Callback* callback,
                     base::SyncSocket::Handle socket,
                     const char* thread_name);
 
   // This tells the audio thread to stop and clean up the data; this is a
   // synchronous process and the thread will stop before the method returns.
   ~AudioDeviceThread() override;
 
+  // Represents a data packet to be received via the socket.
+  struct Packet {
+    uint32_t pending_data;
+    AudioTimestamp timestamp;
+  };
+
  private:
   void ThreadMain() final;
 
   Callback* const callback_;
   const char* thread_name_;
   base::CancelableSyncSocket socket_;
   base::PlatformThreadHandle thread_handle_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioDeviceThread);
 };
 
 }  // namespace media.
 
 #endif  // MEDIA_AUDIO_AUDIO_DEVICE_THREAD_H_