Use ByteStream in downloads system to decouple source and sink.

content/browser/renderer_host/buffered_resource_handler.cc

Index: content/browser/renderer_host/buffered_resource_handler.cc
diff --git a/content/browser/renderer_host/buffered_resource_handler.cc b/content/browser/renderer_host/buffered_resource_handler.cc
index b0de440f1be276bc8369fa386f3c2ca052be6ebd..0c01f6f93f97de0e1a5444c1afdebbd4d80826fa 100644
--- a/content/browser/renderer_host/buffered_resource_handler.cc
+++ b/content/browser/renderer_host/buffered_resource_handler.cc
@@ -281,8 +281,7 @@ bool BufferedResourceHandler::CompleteResponseStarted(int request_id,
         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.
 
@@ -310,8 +309,7 @@ bool BufferedResourceHandler::CompleteResponseStarted(int request_id,
             DownloadSaveInfo(),
             DownloadResourceHandler::OnStartedCallback()));
 
-    if (!UseAlternateResourceHandler(request_id, handler, defer))
-      return false;
+    return UseAlternateResourceHandler(request_id, handler, defer);
   }
 
   if (*defer)