Implement the Notification `timestamp` property

chrome/browser/notifications/notification_ui_manager_android.cc

 // Copyright 2014 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/notifications/notification_ui_manager_android.h"
 
 #include <utility>
 
 #include "base/android/context_utils.h"
 #include "base/android/jni_array.h"
@@ skipping 134 matching lines @@
 
   ScopedJavaLocalRef<jintArray> vibration_pattern =
       base::android::ToJavaIntArray(env, notification.vibration_pattern());
 
   ScopedJavaLocalRef<jstring> profile_id =
       ConvertUTF8ToJavaString(env, profile->GetPath().BaseName().value());
 
   Java_NotificationUIManager_displayNotification(
       env, java_object_.obj(), persistent_notification_id, origin.obj(),
       profile_id.obj(), profile->IsOffTheRecord(), tag.obj(), title.obj(),
-      body.obj(), icon.obj(), vibration_pattern.obj(), notification.silent(),
+      body.obj(), icon.obj(), vibration_pattern.obj(),
+      notification.timestamp().ToJavaTime(), notification.silent(),
       action_titles.obj());
 
   regenerated_notification_infos_[persistent_notification_id] =
       std::make_pair(origin_url.spec(), notification.tag());
 
   notification.delegate()->Display();
 }
 
 bool NotificationUIManagerAndroid::Update(const Notification& notification,
                                           Profile* profile) {
@@ skipping 66 matching lines @@
   return false;
 }
 
 void NotificationUIManagerAndroid::CancelAll() {
   NOTREACHED();
 }
 
 bool NotificationUIManagerAndroid::RegisterNotificationUIManager(JNIEnv* env) {
   return RegisterNativesImpl(env);
 }