Avoid blocking SHChangeNotify call in CreateOrUpdateShortcutLink

Avoid blocking call to SHChangeNotify in CreateOrUpdateShortcutLink by
replacing SHCNF_FLUSH with SHCNF_FLUSHNOWAIT.  The former lead to long
hangs in communication with the windows shell.

Bug: 1502607
Change-Id: Iff65fe026db4600e89811c59aa871ea051f52a9f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5033903
Reviewed-by: David Bienvenu <davidbienvenu@chromium.org>
Reviewed-by: Will Harris <wfh@chromium.org>
Commit-Queue: Chris Davis <chrdavis@microsoft.com>
Cr-Commit-Position: refs/heads/main@{#1225207}
diff --git a/base/win/shortcut.cc b/base/win/shortcut.cc
index 5500017..c8dd648b 100644
--- a/base/win/shortcut.cc
+++ b/base/win/shortcut.cc
@@ -204,7 +204,7 @@
     return false;
 
   SHChangeNotify(shortcut_existed ? SHCNE_UPDATEITEM : SHCNE_CREATE,
-                 SHCNF_PATH | SHCNF_FLUSH, shortcut_path.value().c_str(),
+                 SHCNF_PATH | SHCNF_FLUSHNOWAIT, shortcut_path.value().c_str(),
                  nullptr);
 
   return true;