In WinAura, also kill the Metro viewer process in AttemptExit().

chrome/browser/browser_process_platform_part_mac.mm

+// Copyright (c) 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "chrome/browser/browser_process_platform_part_mac.h"
+#import "chrome/browser/chrome_browser_application_mac.h"
+
+BrowserProcessPlatformPart::BrowserProcessPlatformPart() {
+}
+
+BrowserProcessPlatformPart::~BrowserProcessPlatformPart() {
+}
+
+void BrowserProcessPlatformPart::AttemptExit() {
+  // On the Mac, the application continues to run once all windows are closed.
+  // Terminate will result in a CloseAllBrowsers() call, and once (and if)
+  // that is done, will cause the application to exit cleanly.
+  chrome_browser_application_mac::Terminate();
+}