Revert "[MacOS Host] Fixing a memory leak in the alert dialog"

This reverts commit 65453a44.

Reason for revert: broke the build: https://logs.chromium.org/logs/chromium/buildbucket/cr-buildbucket.appspot.com/8928590708886404784/+/steps/compile/0/stdout

Original change's description:
> [MacOS Host] Fixing a memory leak in the alert dialog
> 
> Follow-up CL fixing a leak identified post check-in.
> 
> Bug: 902041
> Change-Id: Ic900c107f13185fa8c823163b2278990ed543ff2
> Reviewed-on: https://chromium-review.googlesource.com/c/1352030
> Reviewed-by: Robert Sesek <rsesek@chromium.org>
> Commit-Queue: Joe Downing <joedow@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#611777}

TBR=joedow@chromium.org,rsesek@chromium.org

Change-Id: I346b4a43995959ce2c289d5f2ff31feb722b4233
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 902041
Reviewed-on: https://chromium-review.googlesource.com/c/1354231Reviewed-by: Ken Rockot <rockot@google.com>
Commit-Queue: Ken Rockot <rockot@google.com>
Cr-Commit-Position: refs/heads/master@{#611806}

remoting/host/mac/permission_utils.mm

@@ -9,7 +9,6 @@
 #include "base/bind.h"
 #include "base/location.h"
 #include "base/logging.h"
-#include "base/mac/scoped_nsobject.h"
 #include "base/memory/scoped_refptr.h"
 #include "base/single_thread_task_runner.h"
 #include "base/strings/sys_string_conversions.h"
@@ -23,7 +22,7 @@ constexpr int kMinDialogWidthPx = 650;
 constexpr NSString* kServiceScriptName = @"org.chromium.chromoting.me2me.sh";
 
 void ShowPermissionDialog() {
-  base::scoped_nsobject<NSAlert> alert([[NSAlert alloc] init]);
+  NSAlert* alert = [[NSAlert alloc] init];
   [alert setMessageText:l10n_util::GetNSString(
                             IDS_ACCESSIBILITY_PERMISSION_DIALOG_TITLE)];
   [alert setInformativeText: