Make ResourceHandler::OnWillRead able to complete asynchronously.

content/browser/loader/layered_resource_handler.h

 // 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.
 
 #ifndef CONTENT_BROWSER_LOADER_LAYERED_RESOURCE_HANDLER_H_
 #define CONTENT_BROWSER_LOADER_LAYERED_RESOURCE_HANDLER_H_
 
 #include <memory>
 
 #include "content/browser/loader/resource_handler.h"
@@ skipping 19 matching lines @@
   void SetDelegate(Delegate* delegate) override;
   void OnRequestRedirected(
       const net::RedirectInfo& redirect_info,
       ResourceResponse* response,
       std::unique_ptr<ResourceController> controller) override;
   void OnResponseStarted(
       ResourceResponse* response,
       std::unique_ptr<ResourceController> controller) override;
   void OnWillStart(const GURL& url,
                    std::unique_ptr<ResourceController> controller) override;
-  bool OnWillRead(scoped_refptr<net::IOBuffer>* buf,
-                  int* buf_size) override;
+  void OnWillRead(scoped_refptr<net::IOBuffer>* buf,
+                  int* buf_size,
+                  std::unique_ptr<ResourceController> controller) override;
   void OnReadCompleted(int bytes_read,
                        std::unique_ptr<ResourceController> controller) override;
   void OnResponseCompleted(
       const net::URLRequestStatus& status,
       std::unique_ptr<ResourceController> controller) override;
   void OnDataDownloaded(int bytes_downloaded) override;
 
   std::unique_ptr<ResourceHandler> next_handler_;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_LOADER_LAYERED_RESOURCE_HANDLER_H_