Add Browser::SkipCallBeforeUnload so that the browser windows can be closed regardless of beforeunl…

chrome/browser/ui/unload_controller_web_contents_delegate.cc

+// Copyright 2017 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/ui/unload_controller_web_contents_delegate.h"
+
+#include "content/public/browser/web_contents.h"
+
+UnloadControllerWebContentsDelegate::UnloadControllerWebContentsDelegate() {}
+UnloadControllerWebContentsDelegate::~UnloadControllerWebContentsDelegate() {}
+
+bool UnloadControllerWebContentsDelegate::ShouldSuppressDialogs(
+    content::WebContents* source) {
+  return true;
+}
+
+void UnloadControllerWebContentsDelegate::CloseContents(
+    content::WebContents* source) {
+  delete source;
+}