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

net/http/http_auth_handler.h

Index: net/http/http_auth_handler.h
diff --git a/net/http/http_auth_handler.h b/net/http/http_auth_handler.h
index a78ae0c8429beb9d2f12c11d1f44bc660d78ac18..1144e87f771ca95397f47302eada35533e49073e 100644
--- a/net/http/http_auth_handler.h
+++ b/net/http/http_auth_handler.h
@@ -70,8 +70,7 @@ class NET_EXPORT_PRIVATE HttpAuthHandler {
   // call.
   // Otherwise, there was a problem generating a token synchronously, and the
   // value of |*auth_token| is unspecified.
-  int GenerateAuthToken(const string16* username,
-                        const string16* password,
+  int GenerateAuthToken(const AuthCredentials* credentials,
                         const HttpRequestInfo* request,
                         OldCompletionCallback* callback,
                         std::string* auth_token);
@@ -157,8 +156,7 @@ class NET_EXPORT_PRIVATE HttpAuthHandler {
   // |GenerateAuthTokenImpl()} is the auth-scheme specific implementation
   // of generating the next auth token. Callers sohuld use |GenerateAuthToken()|
   // which will in turn call |GenerateAuthTokenImpl()|
-  virtual int GenerateAuthTokenImpl(const string16* username,
-                                    const string16* password,
+  virtual int GenerateAuthTokenImpl(const AuthCredentials* credentials,
                                     const HttpRequestInfo* request,
                                     OldCompletionCallback* callback,
                                     std::string* auth_token) = 0;