RL: Stop source and fire MediaStreamTrack ended event if missing audio input callbacks are detected.

media/audio/audio_input_device.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.
 
 // Low-latency audio capturing class utilizing audio input stream provided
 // by a server (browser) process by use of an IPC interface.
 //
 // Relationship of classes:
 //
 //  AudioInputController                 AudioInputDevice
@@ skipping 41 matching lines @@
 
 #ifndef MEDIA_AUDIO_AUDIO_INPUT_DEVICE_H_
 #define MEDIA_AUDIO_AUDIO_INPUT_DEVICE_H_
 
 #include <memory>
 #include <string>
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "base/memory/shared_memory.h"
+#include "base/time/time.h"
+#include "base/timer/timer.h"
 #include "media/audio/audio_device_thread.h"
 #include "media/audio/audio_input_ipc.h"
 #include "media/audio/scoped_task_runner_observer.h"
 #include "media/base/audio_capturer_source.h"
 #include "media/base/audio_parameters.h"
 #include "media/base/media_export.h"
 
 namespace media {
 
 // TODO(henrika): This class is based on the AudioOutputDevice class and it has
@@ skipping 49 matching lines @@
   // sends IPC messages on that thread.
   void StartUpOnIOThread();
   void ShutDownOnIOThread();
   void SetVolumeOnIOThread(double volume);
   void SetAutomaticGainControlOnIOThread(bool enabled);
 
   // base::MessageLoop::DestructionObserver implementation for the IO loop.
   // If the IO loop dies before we do, we shut down the audio thread from here.
   void WillDestroyCurrentMessageLoop() override;
 
+  // Checks if we have gotten callbacks within a certain time period. If no
+  // callbacks have been received, we report a capture error to the capture
+  // callback. Must be called on IO thread.
+  void CheckIfInputStreamIsAlive();
+
+  // Sets the last callback time |last_callback_time_ms_| to the current time.
+  // SetLastCallbackTimeToNow() posts a task on the IO thread to run
+  // SetLastCallbackTimeToNowOnIOThread() which actually sets the variable. We
+  // don't need high precision so we don't have to care about the delay added
+  // with posting the task.
+  void SetLastCallbackTimeToNow();
+  void SetLastCallbackTimeToNowOnIOThread();
+
   AudioParameters audio_parameters_;
 
   CaptureCallback* callback_;
 
   // A pointer to the IPC layer that takes care of sending requests over to
   // the AudioInputRendererHost.  Only valid when state_ != IPC_CLOSED and must
   // only be accessed on the IO thread.
   std::unique_ptr<AudioInputIPC> ipc_;
 
   // Current state (must only be accessed from the IO thread).  See comments for
@@ skipping 18 matching lines @@
   std::unique_ptr<AudioDeviceThread> audio_thread_;
 
   // Temporary hack to ignore OnStreamCreated() due to the user calling Stop()
   // so we don't start the audio thread pointing to a potentially freed
   // |callback_|.
   //
   // TODO(miu): Replace this by changing AudioCapturerSource to accept the
   // callback via Start(). See http://crbug.com/151051 for details.
   bool stopping_hack_;
 
+  // Mechanism for detecting if we don't get callbacks for some period of time.
+  // |check_alive_timer_| runs the check regularly.
+  // |last_callback_time_| stores the time for the last callback.
+  // Both must only be accessed on the IO thread.
+  // TODO(grunell): Change from TimeTicks to Atomic32 and remove the task
+  // posting in SetLastCallbackTimeToNow(). The Atomic32 variable would have to
+  // represent some time in seconds or tenths of seconds to be able to span over
+  // enough time. Atomic64 cannot be used since it's not supported on 32-bit
+  // platforms.
+  std::unique_ptr<base::RepeatingTimer> check_alive_timer_;
+  base::TimeTicks last_callback_time_;
+
+  // Flags that missing callbacks has been detected. Used for statistics,
+  // reported when stopping. Must only be accessed on the IO thread.
+  bool missing_callbacks_detected_;
+
   DISALLOW_IMPLICIT_CONSTRUCTORS(AudioInputDevice);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_AUDIO_AUDIO_INPUT_DEVICE_H_