Experiment to help track down bug 68766....

chrome/browser/renderer_host/resource_dispatcher_host.cc

Index: chrome/browser/renderer_host/resource_dispatcher_host.cc
===================================================================
--- chrome/browser/renderer_host/resource_dispatcher_host.cc	(revision 70977)
+++ chrome/browser/renderer_host/resource_dispatcher_host.cc	(working copy)
@@ -194,6 +194,24 @@
   return all_error_codes;
 }
 
+#if defined(OS_WIN)
+#pragma warning (disable: 4748)
+#pragma optimize( "", off )
+#endif
+
+// Temporary experiment to help track down http://crbug.com/68766.
+// This should crash if called with an invalid ChromeURLRequestContext.
+// TODO(eroman): Delete this when experiment is complete.
+void CheckContextForBug68766(URLRequestContext* context) {
+  if (context)
+    static_cast<ChromeURLRequestContext*>(context)->IsExternal();
+}
+
+#if defined(OS_WIN)
+#pragma optimize( "", on )
+#pragma warning (default: 4748)
+#endif
+
 }  // namespace
 
 ResourceDispatcherHost::ResourceDispatcherHost()
@@ -349,6 +367,8 @@
   ChromeURLRequestContext* context = filter_->GetURLRequestContext(
       request_id, request_data.resource_type);
 
+  CheckContextForBug68766(context);
+
   // Might need to resolve the blob references in the upload data.
   if (request_data.upload_data && context) {
     context->blob_storage_context()->controller()->
@@ -1301,8 +1321,10 @@
     return;
   }
 
-  if (!defer_start)
+  if (!defer_start) {
+    CheckContextForBug68766(request->context());
     InsertIntoResourceQueue(request, *info);
+  }
 }
 
 void ResourceDispatcherHost::InsertIntoResourceQueue(