[Chromoting] Move DefaultAudioDeviceChangeDetector out of AudioCapturerWin

remoting/host/win/default_audio_device_change_detector.cc

+// Copyright 2017 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 "remoting/host/win/default_audio_device_change_detector.h"
+
+#include <unknwn.h>
+
+#include "base/logging.h"
+
+namespace remoting {
+
+DefaultAudioDeviceChangeDetector::DefaultAudioDeviceChangeDetector(
+    IMMDeviceEnumerator* enumerator)
+    : enumerator_(enumerator) {
+  DCHECK(enumerator_);
+  HRESULT hr = enumerator_->RegisterEndpointNotificationCallback(this);
+  if (FAILED(hr)) {
+    // We cannot predict which kind of error the API may return, but this is not
+    // a fatal error.
+    LOG(ERROR) << "Failed to register IMMNotificationClient, we may not be "
+                  "able to detect the new default audio device. Error "
+               << hr;
+  }
+}
+
+DefaultAudioDeviceChangeDetector::~DefaultAudioDeviceChangeDetector() {
+  enumerator_->UnregisterEndpointNotificationCallback(this);
+}
+
+HRESULT DefaultAudioDeviceChangeDetector::OnDefaultDeviceChanged(
+    EDataFlow flow,
+    ERole role,
+    LPCWSTR pwstrDefaultDevice) {
+  {
+    base::AutoLock lock(lock_);
+    changed_ = true;
+  }
+  return S_OK;
+}
+
+HRESULT DefaultAudioDeviceChangeDetector::QueryInterface(REFIID iid,
+                                                         void** object) {
+  if (iid == IID_IUnknown || iid == __uuidof(IMMNotificationClient)) {
+    *object = static_cast<IMMNotificationClient*>(this);
+    return S_OK;
+  }
+  *object = nullptr;
+  return E_NOINTERFACE;
+}
+
+bool DefaultAudioDeviceChangeDetector::GetAndReset() {
+  bool result = false;
+  {
+    base::AutoLock lock(lock_);
+    result = changed_;
+    changed_ = false;
+  }
+  return result;
+}
+
+}  // namespace remoting