Wrong coordinate is used in ScreenCapturerWinGdi

Wrong coordinate is used in ScreenCapturerWinGdi in change
https://chromium-review.googlesource.com/c/external/webrtc/+/644787

Bug: webrtc:7950
Change-Id: I8a11a4cedc594ce9c5462578e59b4e31b8c79253
Reviewed-on: https://chromium-review.googlesource.com/655257
Reviewed-by: Jamie Walch <jamiewalch@chromium.org>
Commit-Queue: Zijie He <zijiehe@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#19734}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 9ec5da67f0d529eca0185acebcbb3ef6895c668f
diff --git a/modules/desktop_capture/win/screen_capturer_win_gdi.cc b/modules/desktop_capture/win/screen_capturer_win_gdi.cc
index b342e9f..10e3ca4 100644
--- a/modules/desktop_capture/win/screen_capturer_win_gdi.cc
+++ b/modules/desktop_capture/win/screen_capturer_win_gdi.cc
@@ -195,7 +195,8 @@
       return false;
     queue_.ReplaceCurrentFrame(SharedDesktopFrame::Wrap(std::move(buffer)));
   }
-  queue_.current_frame()->set_top_left(screen_rect.top_left());
+  queue_.current_frame()->set_top_left(
+      screen_rect.top_left().subtract(GetFullscreenRect().top_left()));
 
   // Select the target bitmap into the memory dc and copy the rect from desktop
   // to memory.