Output DeviceName from various windows ScreenCapturer related implementations

webrtc/modules/desktop_capture/win/dxgi_duplicator_controller.cc

Index: webrtc/modules/desktop_capture/win/dxgi_duplicator_controller.cc
diff --git a/webrtc/modules/desktop_capture/win/dxgi_duplicator_controller.cc b/webrtc/modules/desktop_capture/win/dxgi_duplicator_controller.cc
index 1c015e4a82a71a4d8e7fffd4e684237bf19a9972..83e0fda5ffec6b5ea30f8085c9186474f2ae9170 100644
--- a/webrtc/modules/desktop_capture/win/dxgi_duplicator_controller.cc
+++ b/webrtc/modules/desktop_capture/win/dxgi_duplicator_controller.cc
@@ -114,6 +114,16 @@ int DxgiDuplicatorController::ScreenCount() {
   return 0;
 }
 
+bool DxgiDuplicatorController::GetDeviceNames(
+    std::vector<std::string>* output) {
+  rtc::CritScope lock(&lock_);
+  if (Initialize()) {
+    GetDeviceNamesUnlocked(output);
+    return true;
+  }
+  return false;
+}
+
 DxgiDuplicatorController::Result
 DxgiDuplicatorController::DoDuplicate(DxgiFrame* frame, int monitor_id) {
   RTC_DCHECK(frame);
@@ -370,6 +380,16 @@ int DxgiDuplicatorController::ScreenCountUnlocked() const {
   return result;
 }
 
+void DxgiDuplicatorController::GetDeviceNamesUnlocked(
+    std::vector<std::string>* output) const {
+  RTC_DCHECK(output);
+  for (auto& duplicator : duplicators_) {
+    for (int i = 0; i < duplicator.screen_count(); i++) {
+      output->push_back(duplicator.GetDeviceName(i));
+    }
+  }
+}
+
 DesktopSize DxgiDuplicatorController::SelectedDesktopSize(
     int monitor_id) const {
   if (monitor_id < 0) {