ui: fix an instance of bugprone-unused-raii

It seems that this constructor call was intended to be used as a scope
guard. In order for that to happen, there has to be a variable name
here.

Bug: 1130379
Change-Id: I3c5f1ec85cefcfebc6d40ca82488423edb8e7ec1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2420916Reviewed-by: Thomas Anderson <thomasanderson@chromium.org>
Commit-Queue: George Burgess <gbiv@chromium.org>
Cr-Commit-Position: refs/heads/master@{#808940}

ui/gfx/x/connection.cc

@@ -322,7 +322,7 @@ void Connection::Sync() {
   if (syncing_)
     return;
   {
-    base::AutoReset<bool>(&syncing_, true);
+    base::AutoReset<bool> auto_reset(&syncing_, true);
     GetInputFocus({}).Sync();
   }
 }