Add AudioOutputController trace events and UMA backed wedge detection.

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/cancelable_callback.h"
 #include "base/memory/ref_counted.h"
+#include "base/timer/timer.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
 // to this output stream. It has an important function that it executes
 // audio operations like play, pause, stop, etc. on a separate thread,
@@ skipping 193 matching lines @@
   void StopStream();
 
   // Helper method that stops, closes, and NULLs |*stream_|.
   void DoStopCloseAndClearStream();
 
   // Sanity-check that entry/exit to OnMoreIOData() by the hardware audio thread
   // happens only between AudioOutputStream::Start() and Stop().
   void AllowEntryToOnMoreIOData();
   void DisallowEntryToOnMoreIOData();
 
+  // Checks if a stream was started successfully but never calls OnMoreIOData().
+  void WedgeCheck();
+
   AudioManager* const audio_manager_;
   const AudioParameters params_;
   EventHandler* const handler_;
 
   // Specifies the device id of the output device to open or empty for the
   // default output device.
   std::string output_device_id_;
 
   // Used by the unified IO to open the correct input device.
   const std::string input_device_id_;
@@ skipping 25 matching lines @@
   const scoped_refptr<base::MessageLoopProxy> message_loop_;
 
 #if defined(AUDIO_POWER_MONITORING)
   // Scans audio samples from OnMoreIOData() as input to compute power levels.
   AudioPowerMonitor power_monitor_;
 
   // Periodic callback to report power levels during playback.
   base::CancelableClosure power_poll_callback_;
 #endif
 
-  // When starting stream we wait for data to become available.
-  // Number of times left.
-  int number_polling_attempts_left_;
+  // Flags when we've asked for a stream to start but it never did.
+  bool wedge_detected_;
+  base::OneShotTimer<AudioOutputController> wedge_timer_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioOutputController);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_AUDIO_AUDIO_OUTPUT_CONTROLLER_H_