Protect WebURLLoaderImpl::Context while receiving responses.

webkit/glue/weburlloader_impl.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.
 
 // An implementation of WebURLLoader in terms of ResourceLoaderBridge.
 
 #include "webkit/glue/weburlloader_impl.h"
 
 #include "base/bind.h"
 #include "base/files/file_path.h"
@@ skipping 633 matching lines @@
   if (info.mime_type == "text/vnd.chromium.ftp-dir") {
     if (show_raw_listing) {
       // Set the MIME type to plain text to prevent any active content.
       response.setMIMEType("text/plain");
     } else {
       // We're going to produce a parsed listing in HTML.
       response.setMIMEType("text/html");
     }
   }
 
+  scoped_refptr<Context> protect(this);

[darin (slow to review), 2013/05/23 14:42:09]

This looks like it'll do the trick to me.  However, I'm not a big fan of
protect(this) patterns.  I usually try to find some way to avoid it if I can. 
Maybe the caller of OnReceivedResponse can retain a reference, etc.  (I need to
study the code more...)

[gavinp, 2013/05/28 16:25:35]

Certainly the caller could, but that would be a bigger change to the code. The
typical call path is ResourceDispatcher::OnReceivedResponse calls through the
ResourceLoaderBridge::Peer interface, which Context implements.

Context is refcounted, but ResourceLoaderBridge::Peer is not.

I've spent some time playing with it, and I'm more comfortable guarding here
than making the abstract class Refcounted. I'll make an upload that does that
for comparison if you like, in the meantime I'd welcome your opinion.

   client_->didReceiveResponse(loader_, response);
 
   // We may have been cancelled after didReceiveResponse, which would leave us
   // without a client and therefore without much need to do further handling.
   if (!client_)
     return;
 
   DCHECK(!ftp_listing_delegate_.get());
   DCHECK(!multipart_delegate_.get());
   if (info.headers && info.mime_type == "multipart/x-mixed-replace") {
@@ skipping 195 matching lines @@
 
 void WebURLLoaderImpl::setDefersLoading(bool value) {
   context_->SetDefersLoading(value);
 }
 
 void WebURLLoaderImpl::didChangePriority(WebURLRequest::Priority new_priority) {
   context_->DidChangePriority(new_priority);
 }
 
 }  // namespace webkit_glue