Only mark a proxy as bad if we have confirmation that another proxy succeeded for the same request.

net/proxy/proxy_service.h

Index: net/proxy/proxy_service.h
diff --git a/net/proxy/proxy_service.h b/net/proxy/proxy_service.h
index ad73b39fa4874c5af5a97a640571bb42f025abd4..cc308dd69bdc8d01b434d29c472e0d0be04af320 100644
--- a/net/proxy/proxy_service.h
+++ b/net/proxy/proxy_service.h
@@ -97,6 +97,11 @@ class NET_EXPORT ProxyService : public NetworkChangeNotifier::IPAddressObserver,
                                 PacRequest** pac_request,
                                 const BoundNetLog& net_log);
 
+  // Called to report that the last proxy connection succeeded.  If |proxy_info|
+  // has a non empty proxy_retry_info map, the proxies that have been tried (and
+  // failed) for this request will be marked as bad.
+  void ReportSuccess(const ProxyInfo& proxy_info);
+
   // Call this method with a non-null |pac_request| to cancel the PAC request.
   void CancelPacRequest(PacRequest* pac_request);