Use AuthCredentials throughout the network stack instead of username/password.

net/http/http_stream_factory.h

Index: net/http/http_stream_factory.h
diff --git a/net/http/http_stream_factory.h b/net/http/http_stream_factory.h
index 31e0cc19b954fe03a1ec399427405d0334557153..913ad380871af4f1dde95bf257d5544d68fc1fb7 100644
--- a/net/http/http_stream_factory.h
+++ b/net/http/http_stream_factory.h
@@ -19,6 +19,7 @@ class GURL;
 
 namespace net {
 
+class AuthCredentials;
 class BoundNetLog;
 class HostMappingRules;
 class HostPortPair;
@@ -132,8 +133,8 @@ class NET_EXPORT_PRIVATE HttpStreamRequest {
   // will have been called.  It now becomes the delegate's responsibility
   // to collect the necessary credentials, and then call this method to
   // resume the HttpStream creation process.
-  virtual int RestartTunnelWithProxyAuth(const string16& username,
-                                         const string16& password) = 0;
+  virtual int RestartTunnelWithProxyAuth(
+      const AuthCredentials& credentials) = 0;
 
   // Returns the LoadState for the request.
   virtual LoadState GetLoadState() const = 0;