Properly handle user cancellation of signin.

chrome/browser/signin/signin_manager.h

Index: chrome/browser/signin/signin_manager.h
diff --git a/chrome/browser/signin/signin_manager.h b/chrome/browser/signin/signin_manager.h
index 61ab8607941ca9caf28c38269cec65a190de9b9a..41a7a366019fbfc1425a62920eb0fe67faf521c4 100644
--- a/chrome/browser/signin/signin_manager.h
+++ b/chrome/browser/signin/signin_manager.h
@@ -308,6 +308,9 @@ class SigninManager : public GaiaAuthConsumer,
   // credentials transfer and load policy.
   void CompleteSigninForNewProfile(Profile* profile,
                                    Profile::CreateStatus status);
+
+  // Cancels the in-progress signin for this profile.
+  void CancelSignin();
 #endif  // defined(ENABLE_CONFIGURATION_POLICY) && !defined(OS_CHROMEOS)
 
   // Invoked once policy has been loaded to complete user signin.