Create default implementations of ContentRendererClient, ContentUtilityClient, and ContentPluginCli…

content/public/utility/content_utility_client.h

 // Copyright (c) 2011 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.
 
 #ifndef CONTENT_PUBLIC_UTILITY_CONTENT_UTILITY_CLIENT_H_
 #define CONTENT_PUBLIC_UTILITY_CONTENT_UTILITY_CLIENT_H_
 #pragma once
 
 #include "content/public/common/content_client.h"
 
 namespace content {
 
 // Embedder API for participating in renderer logic.
-class ContentUtilityClient {
+class CONTENT_EXPORT ContentUtilityClient {
  public:
   // Notifies us that the UtilityThread has been created.
-  virtual void UtilityThreadStarted() = 0;
+  virtual void UtilityThreadStarted() {}
 
   // Allows the embedder to filter messages.
-  virtual bool OnMessageReceived(const IPC::Message& message) = 0;
+  virtual bool OnMessageReceived(const IPC::Message& message);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_UTILITY_CONTENT_UTILITY_CLIENT_H_