Make ResourceHandler::OnWillRead able to complete asynchronously.

content/browser/download/save_file_resource_handler.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 "content/browser/download/save_file_resource_handler.h"
 
 #include "base/bind.h"
 #include "base/logging.h"
 #include "base/message_loop/message_loop.h"
 #include "base/strings/string_number_conversions.h"
@@ skipping 52 matching lines @@
 void SaveFileResourceHandler::OnWillStart(
     const GURL& url,
     std::unique_ptr<ResourceController> controller) {
   if (authorization_state_ == AuthorizationState::AUTHORIZED) {
     controller->Resume();
   } else {
     controller->Cancel();
   }
 }
 
-bool SaveFileResourceHandler::OnWillRead(scoped_refptr<net::IOBuffer>* buf,
-                                         int* buf_size) {
+void SaveFileResourceHandler::OnWillRead(
+    scoped_refptr<net::IOBuffer>* buf,
+    int* buf_size,
+    std::unique_ptr<ResourceController> controller) {
   DCHECK_EQ(AuthorizationState::AUTHORIZED, authorization_state_);
   DCHECK(buf && buf_size);
   if (!read_buffer_.get()) {
     *buf_size = kReadBufSize;
     read_buffer_ = new net::IOBuffer(*buf_size);
   }
   *buf = read_buffer_.get();
-  return true;
+  controller->Resume();
 }
 
 void SaveFileResourceHandler::OnReadCompleted(
     int bytes_read,
     std::unique_ptr<ResourceController> controller) {
   DCHECK_EQ(AuthorizationState::AUTHORIZED, authorization_state_);
   DCHECK(read_buffer_.get());
   // We are passing ownership of this buffer to the save file manager.
   scoped_refptr<net::IOBuffer> buffer;
   read_buffer_.swap(buffer);
@@ skipping 22 matching lines @@
 void SaveFileResourceHandler::OnDataDownloaded(int bytes_downloaded) {
   NOTREACHED();
 }
 
 void SaveFileResourceHandler::set_content_length(
     const std::string& content_length) {
   base::StringToInt64(content_length, &content_length_);
 }
 
 }  // namespace content