Add a QUIC proxy server to the list of QUIC servers supported at start up

net/base/proxy_delegate.h

Index: net/base/proxy_delegate.h
diff --git a/net/base/proxy_delegate.h b/net/base/proxy_delegate.h
index fd50b20b6d015dc8d6056d6bc7813e8d0af50ad7..ad3a2bcafdd6230922f553f940d0e7f131a737ec 100644
--- a/net/base/proxy_delegate.h
+++ b/net/base/proxy_delegate.h
@@ -83,6 +83,10 @@ class NET_EXPORT ProxyDelegate {
   virtual void OnAlternativeProxyBroken(
       const ProxyServer& alternative_proxy_server) = 0;
 
+  // Returns the default alternative proxy server. May return an invalid proxy
+  // server if no valid proxy server is available.
+  virtual ProxyServer GetDefaultAlternativeProxy() const = 0;
+
  private:
   DISALLOW_COPY_AND_ASSIGN(ProxyDelegate);
 };