Substitute ResourceHandlers with dummy ResourceHandler while request is transferred

content/browser/renderer_host/resource_dispatcher_host.cc

Index: content/browser/renderer_host/resource_dispatcher_host.cc
diff --git a/content/browser/renderer_host/resource_dispatcher_host.cc b/content/browser/renderer_host/resource_dispatcher_host.cc
index a210f8de897aaa3ebe2ecf5aab43b8d48fb63a88..ddc0c9c1a004d98defaa7d8ebec7765d477af627 100644
--- a/content/browser/renderer_host/resource_dispatcher_host.cc
+++ b/content/browser/renderer_host/resource_dispatcher_host.cc
@@ -32,6 +32,7 @@
 #include "content/browser/download/save_file_manager.h"
 #include "content/browser/download/save_file_resource_handler.h"
 #include "content/browser/plugin_service_impl.h"
+#include "content/browser/renderer_host/allow_cancel_resource_handler.h"
 #include "content/browser/renderer_host/async_resource_handler.h"
 #include "content/browser/renderer_host/buffered_resource_handler.h"
 #include "content/browser/renderer_host/cross_site_resource_handler.h"
@@ -1303,8 +1304,21 @@ void ResourceDispatcherHost::OnReceivedRedirect(net::URLRequest* request,
   PopulateResourceResponse(request, response);
   if (!info->resource_handler()->OnRequestRedirected(info->request_id(),
                                                      new_url,
-                                                     response, defer_redirect))
+                                                     response,
+                                                     defer_redirect)) {
     CancelRequestInternal(request, false);
+    return;
+  }
+
+  // If a URLRequest is transferred to a new RenderViewHost, its
+  // ResourceHandlers should not received any notifications because they may

[Matt Perry, 2012/01/05 23:52:44]

receive*

[battre, 2012/01/06 02:18:02]

Done.

+  // depend on the state of the old RVH. We set a ResourceHandler that allows
+  // canceling requests, because on shutdown of the RDH all pending requests
+  // are canceled. The RVH of requests that are being transferred may be gone by
+  // that time.
+  GlobalRequestID global_request_id(info->child_id(), info->request_id());
+  if (IsTransferredNavigation(global_request_id))
+    info->set_resource_handler(new AllowCancelResourceHandler());

[battre, 2012/01/05 22:55:17]

We cannot put this code into the TransferNavigationResourceHandler, as resource
handlers are refcounted. We would remove the only reference to the
ResourceHandler while it is being executed.

[Matt Perry, 2012/01/05 23:52:44]

It's perfectly fine to delete an instance of a class while running one of its
methods - just as long as you don't dereference that instance after the fact.
Please move this to the TransferNavigationResourceHandler (make sure it's the
last code that gets executed before returning, and add a comment warning that it
might 'delete this').

[battre, 2012/01/06 02:18:02]

Done. Moved to MarkAsTransferredNavigation as discussed.

 }
 
 void ResourceDispatcherHost::OnAuthRequired(