Use the device listener in Media on windows

media/audio/win/audio_device_listener_win.cc

Index: media/audio/win/audio_device_listener_win.cc
diff --git a/media/audio/win/audio_device_listener_win.cc b/media/audio/win/audio_device_listener_win.cc
index 9312af62cc78b7d3239a10d306c79a6468a74284..78e84302896fc2c15649f06b769308fc2c2c8d35 100644
--- a/media/audio/win/audio_device_listener_win.cc
+++ b/media/audio/win/audio_device_listener_win.cc
@@ -7,6 +7,7 @@
 #include <Audioclient.h>
 
 #include "base/logging.h"
+#include "base/system_monitor/system_monitor.h"
 #include "base/utf_string_conversions.h"
 #include "base/win/scoped_co_mem.h"
 #include "base/win/windows_version.h"
@@ -18,7 +19,8 @@ using base::win::ScopedCoMem;
 namespace media {
 
 AudioDeviceListenerWin::AudioDeviceListenerWin(const base::Closure& listener_cb)
-    : listener_cb_(listener_cb) {
+    : listener_cb_(listener_cb),
+      pending_capture_device_changed_(false) {
   CHECK(CoreAudioUtil::IsSupported());
 
   ScopedComPtr<IMMDeviceEnumerator> device_enumerator(
@@ -101,12 +103,24 @@ STDMETHODIMP AudioDeviceListenerWin::OnDeviceRemoved(LPCWSTR device_id) {
 
 STDMETHODIMP AudioDeviceListenerWin::OnDeviceStateChanged(LPCWSTR device_id,
                                                           DWORD new_state) {
+  if (!pending_capture_device_changed_)

[tommi (sloooow) - chröme, 2012/12/13 13:16:58]

This doesn't seem right.  With this change we ignore all non-default audio
devices.  Is that what you intend to do?

[no longer working on chromium, 2012/12/13 14:54:58]

This flag is to prevent sending ProcessDevicesChanged for each
DeviceStateChanged event.

I tested it on win7, every time a device is changed, it will trigger the
OnDefaultDeviceChanged and multiple OnDeviceStateChanged callbacks. So we need
this.

+    return S_OK;
+
+  base::SystemMonitor* monitor = base::SystemMonitor::Get();
+  if (monitor)
+    monitor->ProcessDevicesChanged(base::SystemMonitor::DEVTYPE_AUDIO_CAPTURE);
+
+  pending_capture_device_changed_ = false;
   return S_OK;
 }
 
 STDMETHODIMP AudioDeviceListenerWin::OnDefaultDeviceChanged(
     EDataFlow flow, ERole role, LPCWSTR new_default_device_id) {
-  // Only listen for output device changes right now...

[tommi (sloooow) - chröme, 2012/12/13 13:16:58]

why remove this comment?

[no longer working on chromium, 2012/12/13 14:54:58]

because we are also listening to capture device changed now.

+  if (role == eCapture) {
+    pending_capture_device_changed_ = true;

[tommi (sloooow) - chröme, 2012/12/13 13:16:58]

Imho this variable should be called |default_capture_device_changed_| since it
is only raised for the default capture device.

Also, what does the 'pending' part of the name mean?

[no longer working on chromium, 2012/12/13 14:54:58]

I changed the name to capture_device_changed_, since it might not be a default
device, but somehow it will trigger the OnDefaultDeviceChanged callback.

I used the word "pending" to make it clear that we are pending the notification
until getting a statechanged callback. 

+    return S_OK;
+  }
+
   if (flow != eConsole && role != eRender)
     return S_OK;