Adds support for capture device enumeration on Windows.

media/audio/win/device_enumeration_win.cc

+// Copyright (c) 2011 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 <MMDeviceAPI.h>
+#include <mmsystem.h>
+#include <Functiondiscoverykeys_devpkey.h>  // MMDeviceAPI.h must come first
+
+#include "media/audio/win/audio_manager_win.h"
+
+#include "base/logging.h"
+#include "base/utf_string_conversions.h"
+#include "base/win/scoped_co_mem.h"
+#include "base/win/scoped_comptr.h"
+
+using media::AudioDeviceNames;
+using base::win::ScopedComPtr;
+using base::win::ScopedCoMem;
+
+bool GetInputDeviceNamesWin(AudioDeviceNames* device_names) {
+  // It is assumed that this method is called from a COM thread, i.e.,
+  // CoInitializeEx() is not called here again to avoid STA/MTA conflicts.
+  ScopedComPtr<IMMDeviceEnumerator> enumerator;
+  HRESULT hr =  CoCreateInstance(__uuidof(MMDeviceEnumerator),
+                                 NULL,
+                                 CLSCTX_INPROC_SERVER,
+                                 __uuidof(IMMDeviceEnumerator),
+                                 enumerator.ReceiveVoid());
+  if (FAILED(hr)) {
+    LOG(WARNING) << "Failed to create IMMDeviceEnumerator: " << std::hex << hr;
+    return false;
+  }
+
+  // Generate a collection of active audio capture endpoint devices.
+  // This method will succeed even if all devices are disabled.
+  ScopedComPtr<IMMDeviceCollection> collection;
+  hr = enumerator->EnumAudioEndpoints(eCapture,
+                                      DEVICE_STATE_ACTIVE,
+                                      collection.Receive());
+  if (FAILED(hr))
+    return false;
+
+  // Retrieve the number of active capture devices.
+  UINT number_of_active_devices = 0;
+  collection->GetCount(&number_of_active_devices);
+  if (number_of_active_devices == 0)
+    return true;
+
+  media::AudioDeviceName device;
+
+  // Loop over all active capture devices and add friendly name and
+  // unique ID to the |device_names| list.
+  for (UINT i = 0; i < number_of_active_devices; ++i) {
+    // Retrieve unique name of endpoint device.
+    // Example: "{0.0.1.00000000}.{8db6020f-18e3-4f25-b6f5-7726c9122574}".
+    ScopedComPtr<IMMDevice> audio_device;
+    ScopedCoMem<WCHAR> endpoint_device_id;
+    hr = collection->Item(i, audio_device.Receive());
+    if (FAILED(hr))
+      continue;
+    audio_device->GetId(&endpoint_device_id);
+
+    // Store the unique name.
+    device.unique_id = WideToUTF8(string16(endpoint_device_id));
+
+    // Retrieve user-friendly name of endpoint device.
+    // Example: "Microphone (Realtek High Definition Audio)".
+    ScopedComPtr<IPropertyStore> properties;
+    hr = audio_device->OpenPropertyStore(STGM_READ, properties.Receive());
+    if (SUCCEEDED(hr)) {
+      PROPVARIANT friendly_name;
+      PropVariantInit(&friendly_name);
+      hr = properties->GetValue(PKEY_Device_FriendlyName, &friendly_name);
+
+      // Store the user-friendly name.
+      if (SUCCEEDED(hr) &&
+          friendly_name.vt == VT_LPWSTR && friendly_name.pwszVal) {
+        device.device_name = WideToUTF8(string16(friendly_name.pwszVal));

[tommi (sloooow) - chröme, 2011/11/22 12:52:37]

Do you need to construct string16 explicitly?  I would have thought that
WideToUTF8(friendly_name.pwszVal) would be enough (and that it would get
implicitly converted to const std::wstring as per the WideToUTF8 prototype)

[henrika (OOO until Aug 14), 2011/11/23 09:19:19]

Thanks. Fixed.

+      }
+      PropVariantClear(&friendly_name);
+    }
+
+    // Add combination of user-friendly and unique name to the output list.
+    device_names->push_back(device);
+  }
+
+  return true;

[tommi (sloooow) - chröme, 2011/11/22 12:52:37]

Should we return false if the returned array is empty?

[henrika (OOO until Aug 14), 2011/11/23 09:19:19]

No, empty is OK.

+}
+
+bool GetInputDeviceNamesWinXP(AudioDeviceNames* device_names) {
+  // Retrieve the number of active waveform input devices.
+  UINT number_of_active_devices = waveInGetNumDevs();
+  if (number_of_active_devices == 0)
+    return true;
+
+  media::AudioDeviceName device;
+  WAVEINCAPS capabilities;
+  MMRESULT err = MMSYSERR_NOERROR;
+
+  // Loop over all active capture devices and add friendly name and
+  // unique ID to the |device_names| list. Note that, for Wave on XP,
+  // the "unique" name will simply be a copy of the friendly name since
+  // there is no safe method to retrieve a unique device name on XP.
+  for (UINT i = 0; i < number_of_active_devices; ++i) {
+    // Retrieve the capabilities of the specified waveform-audio input device.
+    err = waveInGetDevCaps(i,  &capabilities, sizeof(capabilities));
+    if (err != MMSYSERR_NOERROR)
+      continue;
+
+    if (capabilities.szPname != NULL) {
+      // Store the user-friendly name. Max length is MAXPNAMELEN(=32)
+      // characters and the name cane be truncated on XP.
+      // Example: "Microphone (Realtek High Defini".
+      device.device_name = WideToUTF8(string16(capabilities.szPname));

[tommi (sloooow) - chröme, 2011/11/22 12:52:37]

same string16 comment

[henrika (OOO until Aug 14), 2011/11/23 09:19:19]

Done.

+
+      // Store the "unique" name (we use same as friendly name on Windows XP).
+      device.unique_id = WideToUTF8(string16(capabilities.szPname));

[tommi (sloooow) - chröme, 2011/11/22 12:52:37]

and here

[henrika (OOO until Aug 14), 2011/11/23 09:19:19]

Done.

+
+      // Add combination of user-friendly and unique name to the output list.
+      device_names->push_back(device);
+    }
+  }
+
+  return true;
+}