Support Kerberos on Android

net/http/http_auth_sspi_win.h

Index: net/http/http_auth_sspi_win.h
diff --git a/net/http/http_auth_sspi_win.h b/net/http/http_auth_sspi_win.h
index befc1bf10390fc1abed73dd4f83e23d04a271eb0..691ee5e74653af5febc348db3687400a30b176d3 100644
--- a/net/http/http_auth_sspi_win.h
+++ b/net/http/http_auth_sspi_win.h
@@ -17,6 +17,7 @@
 #include <string>
 
 #include "base/strings/string16.h"
+#include "net/base/completion_callback.h"
 #include "net/base/net_export.h"
 #include "net/http/http_auth.h"
 
@@ -123,13 +124,16 @@ class NET_EXPORT_PRIVATE HttpAuthSSPI {
   // Generates an authentication token for the service specified by the
   // Service Principal Name |spn| and stores the value in |*auth_token|.
   // If the return value is not |OK|, then the value of |*auth_token| is
-  // unspecified. ERR_IO_PENDING is not a valid return code.
+  // unspecified.
+  // The function may return |IO_PENDING|, and call |callback| on completion.
+  // |auth_token| must remain valid until the callback has been called.
   // If this is the first round of a multiple round scheme, credentials are
   // obtained using |*credentials|. If |credentials| is NULL, the credentials
   // for the currently logged in user are used instead.
   int GenerateAuthToken(const AuthCredentials* credentials,
                         const std::string& spn,
-                        std::string* auth_token);
+                        std::string* auth_token,
+                        const CompletionCallback& callback);
 
   // Delegation is allowed on the Kerberos ticket. This allows certain servers
   // to act as the user, such as an IIS server retrieiving data from a