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

net/http/http_auth_handler_digest.h

Index: net/http/http_auth_handler_digest.h
diff --git a/net/http/http_auth_handler_digest.h b/net/http/http_auth_handler_digest.h
index 1358a4a23522e2be5da3c1922221d3b3fbbcb808..87ec21036b3c7d2ce459f3e5f247f9db9de2f975 100644
--- a/net/http/http_auth_handler_digest.h
+++ b/net/http/http_auth_handler_digest.h
@@ -84,8 +84,7 @@ class NET_EXPORT_PRIVATE HttpAuthHandlerDigest : public HttpAuthHandler {
  protected:
   virtual bool Init(HttpAuth::ChallengeTokenizer* challenge);
 
-  virtual int GenerateAuthTokenImpl(const string16* username,
-                                    const string16* password,
+  virtual int GenerateAuthTokenImpl(const AuthCredentials* credentials,
                                     const HttpRequestInfo* request,
                                     OldCompletionCallback* callback,
                                     std::string* auth_token);
@@ -148,16 +147,14 @@ class NET_EXPORT_PRIVATE HttpAuthHandlerDigest : public HttpAuthHandler {
   // Build up  the 'response' production.
   std::string AssembleResponseDigest(const std::string& method,
                                      const std::string& path,
-                                     const string16& username,
-                                     const string16& password,
+                                     const AuthCredentials& credentials,
                                      const std::string& cnonce,
                                      const std::string& nc) const;
 
   // Build up  the value for (Authorization/Proxy-Authorization).
   std::string AssembleCredentials(const std::string& method,
                                   const std::string& path,
-                                  const string16& username,
-                                  const string16& password,
+                                  const AuthCredentials& credentials,
                                   const std::string& cnonce,
                                   int nonce_count) const;