Output DeviceName from various windows ScreenCapturer related implementations

webrtc/modules/desktop_capture/win/dxgi_duplicator_controller.h

Index: webrtc/modules/desktop_capture/win/dxgi_duplicator_controller.h
diff --git a/webrtc/modules/desktop_capture/win/dxgi_duplicator_controller.h b/webrtc/modules/desktop_capture/win/dxgi_duplicator_controller.h
index 41a876b1f359490421a66fa38de087e7fb6aa06b..4b4399d7b9612550bac47c01aee29ee213db5991 100644
--- a/webrtc/modules/desktop_capture/win/dxgi_duplicator_controller.h
+++ b/webrtc/modules/desktop_capture/win/dxgi_duplicator_controller.h
@@ -14,6 +14,7 @@
 #include <D3DCommon.h>
 
 #include <atomic>
+#include <string>
 #include <vector>
 
 #include "webrtc/modules/desktop_capture/desktop_geometry.h"
@@ -101,6 +102,12 @@ class DxgiDuplicatorController {
   // support DXGI based capturer, this function returns 0.
   int ScreenCount();
 
+  // Returns the device names of all screens on the system in utf8 encoding.
+  // These screens can be retrieved by an integer in the range of
+  // [0, output->size()). If system does not support DXGI based capturer, this
+  // function returns false.
+  bool GetDeviceNames(std::vector<std::string>* output);
+
  private:
   // DxgiFrameContext calls private Unregister(Context*) function during
   // destructing.
@@ -183,6 +190,8 @@ class DxgiDuplicatorController {
 
   int ScreenCountUnlocked() const;
 
+  void GetDeviceNamesUnlocked(std::vector<std::string>* output) const;
+
   // Returns the desktop size of the selected screen |monitor_id|. Setting
   // |monitor_id| < 0 to return the entire screen size.
   DesktopSize SelectedDesktopSize(int monitor_id) const;