Use ByteStream in downloads system to decouple source and sink.

content/browser/renderer_host/buffered_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/buffered_resource_handler.h"
 
 #include <vector>
 
 #include "base/bind.h"
 #include "base/logging.h"
@@ skipping 263 matching lines @@
       // TODO(abarth): We should abstract the response_code test, but this kind
       //               of check is scattered throughout our codebase.
       request_->CancelWithError(net::ERR_FILE_NOT_FOUND);
       return false;
     }
 
     X509UserCertResourceHandler* x509_cert_handler =
         new X509UserCertResourceHandler(request_,
                                         info->GetChildID(),
                                         info->GetRouteID());
-    if (!UseAlternateResourceHandler(request_id, x509_cert_handler, defer))
-      return false;
+    return UseAlternateResourceHandler(request_id, x509_cert_handler, defer);

[benjhayden, 2012/05/26 20:42:02]

Is it ok to not run next_handler_->OnResponseStarted() if
UseAlternateResourceHandler() returns true? Also if(*defer) return true.

[Randy Smith (Not in Mondays), 2012/05/28 02:51:37]

UseAlternateResourceHandler() takes responsibility when you call it--if you
look, it actually starts using tracking variables as to whether
OnResponseStarted() has been run.

My apologies; this should never have shown up in this CL since it's part of
http://codereview.chromium.org/10451023.  I should have done the proper magic to
do the diff from that CL.  I'll try to make sure this disappears in a future
patch set.  (Not saying you're not welcome to comments on that CL if you *want*
to--just do it on that CL, and you have a small window since I've already gotten
Darin's LGTM :-}.)

   } else if (info->allow_download() && ShouldDownload(NULL)) {
     // Forward the data to the download thread.
 
     if (response_->headers &&  // Can be NULL if FTP.
         response_->headers->response_code() / 100 != 2) {
       // The response code indicates that this is an error page, but we don't
       // know how to display the content.  We follow Firefox here and show our
       // own error page instead of triggering a download.
       // TODO(abarth): We should abstract the response_code test, but this kind
       //               of check is scattered throughout our codebase.
       request_->CancelWithError(net::ERR_FILE_NOT_FOUND);
       return false;
     }
 
     info->set_is_download(true);
 
     scoped_refptr<ResourceHandler> handler(
         host_->CreateResourceHandlerForDownload(
             request_,
             info->GetContext(),
             info->GetChildID(),
             info->GetRouteID(),
             info->GetRequestID(),
             true,  // is_content_initiated
             DownloadSaveInfo(),
             DownloadResourceHandler::OnStartedCallback()));
 
-    if (!UseAlternateResourceHandler(request_id, handler, defer))
-      return false;
+    return UseAlternateResourceHandler(request_id, handler, defer);
   }
 
   if (*defer)
     return true;
 
   return next_handler_->OnResponseStarted(request_id, response_, defer);
 }
 
 bool BufferedResourceHandler::ShouldWaitForPlugins() {
   bool need_plugin_list;
@@ skipping 130 matching lines @@
 
   bool defer = false;
   if (!CompleteResponseStarted(request_id, &defer)) {
     host_->CancelRequest(child_id, request_id, false);
   } else if (!defer && needs_resume) {
     host_->ResumeDeferredRequest(child_id, request_id);
   }
 }
 
 }  // namespace content