Upstream chromium side of modal dialogs for webview.

android_webview/native/aw_web_contents_delegate.cc

 // Copyright (c) 2012 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 "android_webview/native/aw_web_contents_delegate.h"
 
+#include "base/lazy_instance.h"
+#include "android_webview/native/aw_javascript_dialog_creator.h"
+
 namespace android_webview {
 
+static base::LazyInstance<AwJavaScriptDialogCreator>::Leaky
+    g_javascript_dialog_creator = LAZY_INSTANCE_INITIALIZER;
+
 AwWebContentsDelegate::AwWebContentsDelegate(
     JNIEnv* env,
     jobject obj)
     : WebContentsDelegateAndroid(env, obj) {
 }
 
 AwWebContentsDelegate::~AwWebContentsDelegate() {
 }
 
+content::JavaScriptDialogCreator*
+AwWebContentsDelegate::GetJavaScriptDialogCreator() {
+  return g_javascript_dialog_creator.Pointer();
+}
+
 }  // namespace android_webview