enable download protection on CrOS

chrome/browser/download/notification/download_notification_browsertest.cc

 // Copyright 2015 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 "base/command_line.h"
 #include "base/message_loop/message_loop.h"
 #include "base/path_service.h"
 #include "base/run_loop.h"
 #include "base/strings/utf_string_conversions.h"
 #include "chrome/browser/chromeos/profiles/profile_helper.h"
@@ skipping 212 matching lines @@
   explicit TestChromeDownloadManagerDelegate(Profile* profile)
       : ChromeDownloadManagerDelegate(profile), opened_(false) {}
   ~TestChromeDownloadManagerDelegate() override {}
 
   // ChromeDownloadManagerDelegate override:
   void OpenDownload(content::DownloadItem* item) override { opened_ = true; }
 
   // Return if  the download is opened.
   bool opened() const { return opened_; }
 
+ protected:
+  // Disable DownloadProtectionService in order to disable content checking.
+  safe_browsing::DownloadProtectionService* GetDownloadProtectionService()
+      override {
+    return nullptr;
+  }
+
  private:
   bool opened_;
 };
 
 // Utility method to retrieve a message center.
 message_center::MessageCenter* GetMessageCenter() {
   return message_center::MessageCenter::Get();
 }
 
 // Utility method to retrieve a notification object by id.
@@ skipping 992 matching lines @@
   EXPECT_EQ(message_center::NOTIFICATION_TYPE_BASE_FORMAT,
             GetNotification(notification_id_user1)->type());
   EXPECT_EQ(message_center::NOTIFICATION_TYPE_BASE_FORMAT,
             GetNotification(notification_id_user2_1)->type());
   // Normal notifications for user2.
   EXPECT_EQ(message_center::NOTIFICATION_TYPE_BASE_FORMAT,
             GetNotification(notification_id_user2_1)->type());
   EXPECT_EQ(message_center::NOTIFICATION_TYPE_BASE_FORMAT,
             GetNotification(notification_id_user2_2)->type());
 }