Ensures that audio tasks cannot run after AudioManager is deleted.

media/audio/alsa/audio_manager_alsa.cc

 // 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.
 
 #include "media/audio/alsa/audio_manager_alsa.h"
 
 #include <stddef.h>
 
 #include "base/command_line.h"
 #include "base/environment.h"
@@ skipping 60 matching lines @@
       command_line.AppendArg("input");
       break;
     default:
       LOG(ERROR) << "Failed to show audio input settings: we don't know "
                  << "what command to use for your desktop environment.";
       return;
   }
   base::LaunchProcess(command_line, base::LaunchOptions());
 }
 
-// Implementation of AudioManager.
+AudioManagerAlsa::AudioManagerAlsa(std::unique_ptr<AudioThread> audio_thread,
+                                   AudioLogFactory* audio_log_factory)
+    : AudioManagerBase(std::move(audio_thread), audio_log_factory),
+      wrapper_(new AlsaWrapper()) {
+  SetMaxOutputStreamsAllowed(kMaxOutputStreams);
+}
+
+AudioManagerAlsa::~AudioManagerAlsa() = default;
+
+void AudioManagerAlsa::ShutdownOnAudioThread() {
+  AudioManagerBase::ShutdownOnAudioThread();
+  wrapper_.reset();

[o1ka, 2017/05/10 15:57:56]

Add a comment why we must do it now?

[alokp, 2017/05/10 18:04:03]

Actually we do not need to explicitly destroy alsa wrapper on the audio thread.
Reverted changes in this file.

+}
+
 bool AudioManagerAlsa::HasAudioOutputDevices() {
   return HasAnyAlsaAudioDevice(kStreamPlayback);
 }
 
 bool AudioManagerAlsa::HasAudioInputDevices() {
   return HasAnyAlsaAudioDevice(kStreamCapture);
 }
 
-AudioManagerAlsa::AudioManagerAlsa(
-    scoped_refptr<base::SingleThreadTaskRunner> task_runner,
-    scoped_refptr<base::SingleThreadTaskRunner> worker_task_runner,
-    AudioLogFactory* audio_log_factory)
-    : AudioManagerBase(std::move(task_runner),
-                       std::move(worker_task_runner),
-                       audio_log_factory),
-      wrapper_(new AlsaWrapper()) {
-  SetMaxOutputStreamsAllowed(kMaxOutputStreams);
-}
-
-AudioManagerAlsa::~AudioManagerAlsa() {
-  Shutdown();
-}
-
 void AudioManagerAlsa::ShowAudioInputSettings() {
   ShowLinuxAudioInputSettings();
 }
 
 void AudioManagerAlsa::GetAudioInputDeviceNames(
     AudioDeviceNames* device_names) {
   DCHECK(device_names->empty());
   GetAlsaAudioDevices(kStreamCapture, device_names);
 }
 
@@ skipping 252 matching lines @@
   if (base::CommandLine::ForCurrentProcess()->HasSwitch(
           switches::kAlsaInputDevice)) {
     device_name = base::CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
         switches::kAlsaInputDevice);
   }
 
   return new AlsaPcmInputStream(this, device_name, params, wrapper_.get());
 }
 
 }  // namespace media