win: Fix black pixel artifact at right and bottom

ui/views/win/hwnd_message_handler.cc

Index: ui/views/win/hwnd_message_handler.cc
diff --git a/ui/views/win/hwnd_message_handler.cc b/ui/views/win/hwnd_message_handler.cc
index d8c14ee9b2776f12091f4af804e3da9a69df6ff0..9280529fa2770fbd426543ed4beb69536e2763fe 100644
--- a/ui/views/win/hwnd_message_handler.cc
+++ b/ui/views/win/hwnd_message_handler.cc
@@ -2121,6 +2121,10 @@ void HWNDMessageHandler::OnSize(UINT param, const gfx::Size& size) {
   }
 }
 
+void HWNDMessageHandler::OnSizing(UINT edge, RECT* rect) {
+  delegate_->HandleSizing(edge, rect);
+}
+
 void HWNDMessageHandler::OnSysCommand(UINT notification_code,
                                       const gfx::Point& point) {
   if (!delegate_->ShouldHandleSystemCommands())