Forward the number of skipped frames by the OS in audio playout.

media/audio/audio_output_controller.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_OUTPUT_CONTROLLER_H_
 #define MEDIA_AUDIO_AUDIO_OUTPUT_CONTROLLER_H_
 
 #include "base/atomic_ref_count.h"
 #include "base/callback.h"
 #include "base/memory/ref_counted.h"
+#include "base/threading/thread_checker.h"
 #include "base/timer/timer.h"
 #include "build/build_config.h"
 #include "media/audio/audio_io.h"
 #include "media/audio/audio_manager.h"
 #include "media/audio/audio_power_monitor.h"
 #include "media/audio/audio_source_diverter.h"
 #include "media/audio/simple_sources.h"
 #include "media/base/media_export.h"
 
 // An AudioOutputController controls an AudioOutputStream and provides data
@@ skipping 54 matching lines @@
   // A synchronous reader interface used by AudioOutputController for
   // synchronous reading.
   // TODO(crogers): find a better name for this class and the Read() method
   // now that it can handle synchronized I/O.
   class SyncReader {
    public:
     virtual ~SyncReader() {}
 
     // Notify the synchronous reader the number of bytes in the
     // AudioOutputController not yet played. This is used by SyncReader to
-    // prepare more data and perform synchronization.
-    virtual void UpdatePendingBytes(uint32 bytes) = 0;
+    // prepare more data and perform synchronization. Also inform about if any
+    // frames has been skipped by the renderer (typically the OS). The renderer
+    // source can handle this appropriately depending on the type of source. An
+    // ordinary file playout would ignore this.
+    virtual void UpdatePendingBytes(uint32_t bytes,
+                                    uint32_t frames_skipped) = 0;
 
     // Attempts to completely fill |dest|, zeroing |dest| if the request can not
     // be fulfilled (due to timeout).
     virtual void Read(AudioBus* dest) = 0;
 
     // Close this synchronous reader.
     virtual void Close() = 0;
   };
 
   // Factory method for creating an AudioOutputController.
@@ skipping 49 matching lines @@
   //
   // Changing the output device causes the controller to go through
   // the same state transition back to the current state as a call to
   // OnDeviceChange (unless it is currently diverting, see
   // Start/StopDiverting below, in which case the state transition
   // will happen when StopDiverting is called).
   void SwitchOutputDevice(const std::string& output_device_id,
                           const base::Closure& callback);
 
   // AudioSourceCallback implementation.
-  int OnMoreData(AudioBus* dest, uint32 total_bytes_delay) override;
+  int OnMoreData(AudioBus* dest,
+                 uint32_t total_bytes_delay,
+                 uint32_t frames_skipped) override;
   void OnError(AudioOutputStream* stream) override;
 
   // AudioDeviceListener implementation.  When called AudioOutputController will
   // shutdown the existing |stream_|, transition to the kRecreating state,
   // create a new stream, and then transition back to an equivalent state prior
   // to being called.
   void OnDeviceChange() override;
 
   // AudioSourceDiverter implementation.
   const AudioParameters& GetAudioParameters() override;
@@ skipping 90 matching lines @@
   // be accessed while |error_lock_| is held.
   bool ignore_errors_during_stop_close_;
   base::Lock error_lock_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioOutputController);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_AUDIO_AUDIO_OUTPUT_CONTROLLER_H_