Implement newly designed sign-in related histograms for desktop platorms.

chrome/browser/ui/sync/one_click_signin_sync_starter.cc

Index: chrome/browser/ui/sync/one_click_signin_sync_starter.cc
diff --git a/chrome/browser/ui/sync/one_click_signin_sync_starter.cc b/chrome/browser/ui/sync/one_click_signin_sync_starter.cc
index 61e6906612f8d85fedea7328cdf720a4e5eab0fb..f55557cfe2bb337f18462c18839f0009110bd6ea 100644
--- a/chrome/browser/ui/sync/one_click_signin_sync_starter.cc
+++ b/chrome/browser/ui/sync/one_click_signin_sync_starter.cc
@@ -429,6 +429,11 @@ void OneClickSigninSyncStarter::SigninFailed(
 }
 
 void OneClickSigninSyncStarter::SigninSuccess() {
+  const GURL& current_url = web_contents()->GetURL();

[Roger Tawa OOO till Jul 10th, 2015/12/03 18:18:06]

It seems the web contents could be null sometimes.  I think it might be safer to
pass the access point and reason to the ctor and save them as members.

[gogerald1, 2015/12/03 19:03:18]

Done.

+  signin_metrics::LogSigninAccessPointCompleted(
+      signin::GetAccessPointForPromoURL(current_url));
+  signin_metrics::LogSigninReason(
+      signin::GetSigninReasonForPromoURL(current_url));
 }
 
 void OneClickSigninSyncStarter::AccountAddedToCookie(