Output DeviceName from various windows ScreenCapturer related implementations

webrtc/modules/desktop_capture/win/screen_capture_utils.cc

Index: webrtc/modules/desktop_capture/win/screen_capture_utils.cc
diff --git a/webrtc/modules/desktop_capture/win/screen_capture_utils.cc b/webrtc/modules/desktop_capture/win/screen_capture_utils.cc
index 9fa5c8b12db42a1816998c224ea25947b2b7b1ff..d06c869567382d223a2d27aaf38ee424c7063b87 100644
--- a/webrtc/modules/desktop_capture/win/screen_capture_utils.cc
+++ b/webrtc/modules/desktop_capture/win/screen_capture_utils.cc
@@ -13,11 +13,16 @@
 #include <windows.h>
 
 #include "webrtc/rtc_base/checks.h"
+#include "webrtc/rtc_base/win32.h"
 
 namespace webrtc {
 
-bool GetScreenList(DesktopCapturer::SourceList* screens) {
-  RTC_DCHECK(screens->size() == 0);
+bool GetScreenList(DesktopCapturer::SourceList* screens,
+                   std::vector<std::string>* device_names /* = nullptr */) {
+  RTC_DCHECK_EQ(screens->size(), 0U);
+  if (device_names) {
+    RTC_DCHECK_EQ(device_names->size(), 0U);
+  }
 
   BOOL enum_result = TRUE;
   for (int device_index = 0;; ++device_index) {
@@ -34,6 +39,9 @@ bool GetScreenList(DesktopCapturer::SourceList* screens) {
       continue;
 
     screens->push_back({device_index, std::string()});
+    if (device_names) {
+      device_names->push_back(rtc::ToUtf8(device.DeviceName));
+    }
   }
   return true;
 }