Don't wait to close tabs waiting for JavaScript dialogs.

content/browser/frame_host/render_frame_host_delegate.cc

 // Copyright 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 <stddef.h>
 
 #include "base/callback.h"
 #include "base/strings/string16.h"
 #include "build/build_config.h"
 #include "content/browser/frame_host/render_frame_host_delegate.h"
 #include "ipc/ipc_message.h"
 #include "ui/gfx/native_widget_types.h"
 #include "url/gurl.h"
 
 namespace content {
 
 bool RenderFrameHostDelegate::OnMessageReceived(
     RenderFrameHost* render_view_host,
     const IPC::Message& message) {
   return false;
 }
 
 const GURL& RenderFrameHostDelegate::GetMainFrameLastCommittedURL() const {
   return GURL::EmptyGURL();
 }
 
+bool RenderFrameHostDelegate::IsJavaScriptDialogShowing() const {
+  return false;
+}
+
 bool RenderFrameHostDelegate::AddMessageToConsole(
     int32_t level,
     const base::string16& message,
     int32_t line_no,
     const base::string16& source_id) {
   return false;
 }
 
 WebContents* RenderFrameHostDelegate::GetAsWebContents() {
   return NULL;
@@ skipping 44 matching lines @@
     SiteInstance* source_site_instance) const {
   return false;
 }
 
 std::unique_ptr<WebUIImpl>
 RenderFrameHostDelegate::CreateWebUIForRenderFrameHost(const GURL& url) {
   return nullptr;
 }
 
 }  // namespace content