DesktopRect::UnionWith() to extend current rect to cover the input rect

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 576267bbfa6ce93d116de984a6d15b9faec93db1..c17bd1481c7fffa9e09939e3fbcb75f70deaee87 100644
--- a/webrtc/modules/desktop_capture/win/dxgi_duplicator_controller.cc
+++ b/webrtc/modules/desktop_capture/win/dxgi_duplicator_controller.cc
@@ -182,17 +182,7 @@ bool DxgiDuplicatorController::DoInitialize() {
       d3d_info_.min_feature_level = feature_level;
     }
 
-    if (desktop_rect_.is_empty()) {
-      desktop_rect_ = duplicators_.back().desktop_rect();
-    } else {
-      const DesktopRect& left = desktop_rect_;
-      const DesktopRect& right = duplicators_.back().desktop_rect();
-      desktop_rect_ =
-          DesktopRect::MakeLTRB(std::min(left.left(), right.left()),
-                                std::min(left.top(), right.top()),
-                                std::max(left.right(), right.right()),
-                                std::max(left.bottom(), right.bottom()));
-    }
+    desktop_rect_.UnionWith(duplicators_.back().desktop_rect());
   }
   TranslateRect();