Use ByteStream in downloads system to decouple source and sink.

content/browser/renderer_host/x509_user_cert_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/renderer_host/x509_user_cert_resource_handler.h"
 
 #include "base/string_util.h"
 #include "content/browser/renderer_host/resource_request_info_impl.h"
 #include "content/public/browser/content_browser_client.h"
 #include "content/public/common/resource_response.h"
@@ skipping 97 matching lines @@
   if (resource_buffer_) {
       cert = net::X509Certificate::CreateFromBytes(resource_buffer_->data(),
                                                    content_length_);
   }
   GetContentClient()->browser()->AddNewCertificate(
       request_, cert, render_process_host_id_, render_view_id_);
   return true;
 }
 
 void X509UserCertResourceHandler::AssembleResource() {
-  size_t assembled_bytes = 0;
-  resource_buffer_ = AssembleData(buffer_, &assembled_bytes);
-  DCHECK_EQ(content_length_, assembled_bytes);
+  // 0-length IOBuffers are not allowed.
+  if (content_length_ == 0) {
+    resource_buffer_ = NULL;
+    return;
+  }
+
+  // Create the new buffer.
+  resource_buffer_ = new net::IOBuffer(content_length_);
+
+  // Copy the data into it.
+  size_t bytes_copied = 0;
+  for (size_t i = 0; i < buffer_.size(); ++i) {
+    net::IOBuffer* data = buffer_[i].first;
+    size_t data_len = buffer_[i].second;
+    DCHECK(data != NULL);
+    DCHECK_LE(bytes_copied + data_len, content_length_);
+    memcpy(resource_buffer_->data() + bytes_copied, data->data(), data_len);
+    bytes_copied += data_len;
+  }
+  DCHECK_EQ(content_length_, bytes_copied);
 }
 
 }  // namespace content