Avoid re-starting a ExternalCCResultFetcher if a previous has finished or timed out.

components/signin/core/browser/gaia_cookie_manager_service.cc

Index: components/signin/core/browser/gaia_cookie_manager_service.cc
diff --git a/components/signin/core/browser/gaia_cookie_manager_service.cc b/components/signin/core/browser/gaia_cookie_manager_service.cc
index 28f30f1d2ffab1aa02322776bfcc0253688d930f..cbf3f5e21aba8b977c86126b15c2931aa1d438a2 100644
--- a/components/signin/core/browser/gaia_cookie_manager_service.cc
+++ b/components/signin/core/browser/gaia_cookie_manager_service.cc
@@ -284,7 +284,8 @@ void GaiaCookieManagerService::ExternalCcResultFetcher::
   // StartFetchingMergeSession, we can assume we need to call
   // StartFetchingMergeSession. If this assumption becomes invalid, a Callback
   // will need to be passed to Start() and Run() here.
-  helper_->StartFetchingMergeSession();
+  if (!helper_->uber_token_.empty())
+    helper_->StartFetchingMergeSession();

[Roger Tawa OOO till Jul 10th, 2017/02/21 16:15:16]

I wonder if you need to explicitly call OnMergeSessionFailure() in this case to
make sure pending requests are still handled.  Does that make sense?

[msarda, 2017/02/23 17:29:22]

After you reply, I've debugged this more carefully. I have updated the CL
description and went for a different fix.

 }
 
 GaiaCookieManagerService::GaiaCookieManagerService(