Handle audio device changes on Windows.

media/audio/win/audio_manager_win.cc

 // 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.
 
 #include "media/audio/audio_io.h"
 
 #include <windows.h>
 #include <objbase.h>  // This has to be before initguid.h
 #include <initguid.h>
 #include <mmsystem.h>
 #include <setupapi.h>
 
+#include "base/bind.h"
+#include "base/bind_helpers.h"
 #include "base/basictypes.h"
 #include "base/command_line.h"
 #include "base/file_path.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/message_loop.h"
 #include "base/path_service.h"
 #include "base/process_util.h"
 #include "base/string_number_conversions.h"
 #include "base/string_util.h"
 #include "media/audio/audio_util.h"
 #include "media/audio/win/audio_low_latency_input_win.h"
 #include "media/audio/win/audio_low_latency_output_win.h"
 #include "media/audio/win/audio_manager_win.h"
 #include "media/audio/win/audio_unified_win.h"
 #include "media/audio/win/device_enumeration_win.h"
@@ skipping 89 matching lines @@
 }
 
 bool AudioManagerWin::HasAudioOutputDevices() {
   return (::waveOutGetNumDevs() != 0);
 }
 
 bool AudioManagerWin::HasAudioInputDevices() {
   return (::waveInGetNumDevs() != 0);
 }
 
+void AudioManagerWin::InitializeOnAudioThread() {
+  // AudioDeviceListenerWin must be initialized on a COM thread.
+  output_device_listener_.reset(new AudioDeviceListenerWin(this));
+}
+
 string16 AudioManagerWin::GetAudioInputDeviceModel() {
   // Get the default audio capture device and its device interface name.
   DWORD device_id = 0;
   waveInMessage(reinterpret_cast<HWAVEIN>(WAVE_MAPPER),
                 DRVM_MAPPER_PREFERRED_GET,
                 reinterpret_cast<DWORD_PTR>(&device_id), NULL);
   ULONG device_interface_name_size = 0;
   waveInMessage(reinterpret_cast<HWAVEIN>(device_id),
                 DRV_QUERYDEVICEINTERFACESIZE,
                 reinterpret_cast<DWORD_PTR>(&device_interface_name_size), 0);
@@ skipping 202 matching lines @@
     bits_per_sample = 16;
     channel_layout = WASAPIAudioOutputStream::HardwareChannelLayout();
   }
 
   // TODO(dalecurtis): This should include hardware bits per channel eventually.
   return AudioParameters(
       AudioParameters::AUDIO_PCM_LOW_LATENCY, channel_layout,
       sample_rate, bits_per_sample, GetAudioHardwareBufferSize());
 }
 
+void AudioManagerWin::OnDeviceChange() {
+  // Only fire device changes if low latency output is supported.
+  if (!media::IsWASAPISupported())

[scherkus (not reviewing), 2012/10/24 04:27:09]

This is impossible because your check for the equivalent statement when creating
ADLWin during creation.

I'd like to isolate WASAPI/Vista-checking code to the managers if at all
possible.

How about:
  * ADLWin documents + CHECK()s we're on the right OS
  * AMWin doesn't create an ADLWin if we're not on the right OS
  * This method DCHECKs

[DaleCurtis, 2012/10/24 19:27:29]

Done.

+    return;
+
+  GetMessageLoop()->PostTask(FROM_HERE, base::Bind(
+      &AudioManagerWin::NotifyAllOutputDeviceChangeListeners,
+      base::Unretained(this)));
+}
+
 }  // namespace media