Ensure Dxgi duplicator works correctly in session 0

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 c9838ad7a1e5d63c918da9b22fcde0c0276d0dac..ff7b5a31d5cca052a69cd68d0e29e6b720a4ab80 100644
--- a/webrtc/modules/desktop_capture/win/dxgi_duplicator_controller.h
+++ b/webrtc/modules/desktop_capture/win/dxgi_duplicator_controller.h
@@ -59,6 +59,7 @@ class DxgiDuplicatorController {
 
   enum class Result {
     SUCCEEDED,
+    UNSUPPORTED_SESSION,
     FRAME_PREPARE_FAILED,
     INITIALIZATION_FAILED,
     DUPLICATION_FAILED,
@@ -196,6 +197,8 @@ class DxgiDuplicatorController {
   std::vector<DxgiAdapterDuplicator> duplicators_;
   D3dInfo d3d_info_;
   ResolutionChangeDetector resolution_change_detector_;
+  // A number to indicate how many succeeded duplications have been performed.
+  uint32_t succeeded_duplications_ = 0;
 };
 
 }  // namespace webrtc