Fix a screen capture issue on retina macOS devices.

webrtc/modules/desktop_capture/screen_capturer_mac.mm

Index: webrtc/modules/desktop_capture/screen_capturer_mac.mm
diff --git a/webrtc/modules/desktop_capture/screen_capturer_mac.mm b/webrtc/modules/desktop_capture/screen_capturer_mac.mm
index f11b36d2d2001d6fd0079d8d9464a1dcfd7c89fb..b1d7c9048e91d3c482fc249eaa5db701b61279cc 100644
--- a/webrtc/modules/desktop_capture/screen_capturer_mac.mm
+++ b/webrtc/modules/desktop_capture/screen_capturer_mac.mm
@@ -991,8 +991,10 @@ void ScreenCapturerMac::ScreenRefresh(CGRectCount count,
 
   DesktopRegion region;
   for (CGRectCount i = 0; i < count; ++i) {
-    // Convert from Density-Independent Pixel to physical pixel coordinates.
-    DesktopRect rect = ScaleAndRoundCGRect(rect_array[i], dip_to_pixel_scale_);
+    // All rects are already in physical pixel coordinates.
+    DesktopRect rect = DesktopRect::MakeXYWH(
+        rect_array[i].origin.x, rect_array[i].origin.y,
+        rect_array[i].size.width, rect_array[i].size.height);
     region.AddRect(rect);
   }