Remove calls to MessageLoop::current() in media.

media/audio/alsa/alsa_output.h

 // Copyright 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.
 //
 // Creates an output stream based on the ALSA PCM interface.
 //
 // On device write failure, the stream will move itself to an invalid state.
 // No more data will be pulled from the data source, or written to the device.
 // All calls to public API functions will either no-op themselves, or return an
 // error if possible.  Specifically, If the stream is in an error state, Open()
@@ skipping 12 matching lines @@
 
 #include <alsa/asoundlib.h>
 #include <stdint.h>
 
 #include <memory>
 #include <string>
 
 #include "base/compiler_specific.h"
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
+#include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
+#include "base/single_thread_task_runner.h"
+#include "base/threading/non_thread_safe.h"
 #include "base/time/time.h"
 #include "media/audio/audio_io.h"
 #include "media/base/audio_parameters.h"
 
-namespace base {
-class MessageLoop;
-}
-
 namespace media {
 
 class AlsaWrapper;
 class AudioManagerBase;
 class ChannelMixer;
 class SeekableBuffer;
 
-class MEDIA_EXPORT AlsaPcmOutputStream : public AudioOutputStream {
+class MEDIA_EXPORT AlsaPcmOutputStream : public AudioOutputStream,
+                                         public base::NonThreadSafe {
  public:
   // String for the generic "default" ALSA device that has the highest
   // compatibility and chance of working.
   static const char kDefaultDevice[];
 
   // Pass this to the AlsaPcmOutputStream if you want to attempt auto-selection
   // of the audio device.
   static const char kAutoSelectDevice[];
 
   // Prefix for device names to enable ALSA library resampling.
   static const char kPlugPrefix[];
 
   // The minimum latency that is accepted by the device.
   static const uint32_t kMinLatencyMicros;
 
   // Create a PCM Output stream for the ALSA device identified by
   // |device_name|.  The AlsaPcmOutputStream uses |wrapper| to communicate with
   // the alsa libraries, allowing for dependency injection during testing.  All
   // requesting of data, and writing to the alsa device will be done on
-  // |message_loop|.
+  // the current thread.
   //
   // If unsure of what to use for |device_name|, use |kAutoSelectDevice|.
   AlsaPcmOutputStream(const std::string& device_name,
                       const AudioParameters& params,
                       AlsaWrapper* wrapper,
                       AudioManagerBase* manager);
 
   ~AlsaPcmOutputStream() override;
 
   // Implementation of AudioOutputStream.
@@ skipping 57 matching lines @@
   // Attempts to find the best matching linux audio device for the given number
   // of channels.  This function will set |device_name_| and |channel_mixer_|.
   snd_pcm_t* AutoSelectDevice(uint32_t latency);
 
   // Functions to safeguard state transitions.  All changes to the object state
   // should go through these functions.
   bool CanTransitionTo(InternalState to);
   InternalState TransitionTo(InternalState to);
   InternalState state();
 
-  // Returns true when we're on the audio thread or if the audio thread's
-  // message loop is NULL (which will happen during shutdown).
-  bool IsOnAudioThread() const;
-
   // API for Proxying calls to the AudioSourceCallback provided during
   // Start().
   //
   // TODO(ajwong): This is necessary because the ownership semantics for the
   // |source_callback_| object are incorrect in AudioRenderHost. The callback
   // is passed into the output stream, but ownership is not transfered which
   // requires a synchronization on access of the |source_callback_| to avoid
   // using a deleted callback.
   int RunDataCallback(AudioBus* audio_bus, uint32_t total_bytes_delay);
   void RunErrorCallback(int code);
@@ skipping 23 matching lines @@
   // writing to the ALSA device.  This is set because the device has entered
   // an unrecoverable error state, or the ClosedTask() has executed.
   bool stop_stream_;
 
   // Wrapper class to invoke all the ALSA functions.
   AlsaWrapper* wrapper_;
 
   // Audio manager that created us.  Used to report that we've been closed.
   AudioManagerBase* manager_;
 
-  // Message loop to use for polling. The object is owned by the AudioManager.
-  // We hold a reference to the audio thread message loop since
-  // AudioManagerBase::ShutDown() can invalidate the message loop pointer
-  // before the stream gets deleted.
-  base::MessageLoop* message_loop_;
+  // Task runner to use for polling.
+  const scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
 
   // Handle to the actual PCM playback device.
   snd_pcm_t* playback_handle_;
 
   std::unique_ptr<media::SeekableBuffer> buffer_;
   uint32_t frames_per_packet_;
 
   InternalState state_;
   float volume_;  // Volume level from 0.0 to 1.0.
 
@@ skipping 13 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(AlsaPcmOutputStream);
 };
 
 MEDIA_EXPORT std::ostream& operator<<(std::ostream& os,
                                       AlsaPcmOutputStream::InternalState);
 
 };  // namespace media
 
 #endif  // MEDIA_AUDIO_ALSA_ALSA_OUTPUT_H_