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

chrome/browser/ui/webui/app_launcher_login_handler.cc

Index: chrome/browser/ui/webui/app_launcher_login_handler.cc
diff --git a/chrome/browser/ui/webui/app_launcher_login_handler.cc b/chrome/browser/ui/webui/app_launcher_login_handler.cc
index c5cdb440d2d17b81fe5ff23470fd6358e0a92e53..ef768aa1ea83035b5de880ef4e30649bb04e6235 100644
--- a/chrome/browser/ui/webui/app_launcher_login_handler.cc
+++ b/chrome/browser/ui/webui/app_launcher_login_handler.cc
@@ -126,11 +126,11 @@ void AppLauncherLoginHandler::HandleShowSyncLoginUI(
     return;
 
   // The user isn't signed in, show the sign in promo.
-  signin_metrics::Source source =
-      web_contents->GetURL().spec() == chrome::kChromeUIAppsURL ?
-          signin_metrics::SOURCE_APPS_PAGE_LINK :
-          signin_metrics::SOURCE_NTP_LINK;
-  chrome::ShowBrowserSignin(browser, source);
+  signin_metrics::AccessPoint access_point =
+      web_contents->GetURL().spec() == chrome::kChromeUIAppsURL
+          ? signin_metrics::ACCESS_POINT_APPS_PAGE_LINK
+          : signin_metrics::ACCESS_POINT_NTP_LINK;
+  chrome::ShowBrowserSignin(browser, access_point);
   RecordInHistogram(NTP_SIGN_IN_PROMO_CLICKED);
 }
 
@@ -160,7 +160,7 @@ void AppLauncherLoginHandler::HandleShowAdvancedLoginUI(
   Browser* browser =
       chrome::FindBrowserWithWebContents(web_ui()->GetWebContents());
   if (browser)
-    chrome::ShowBrowserSignin(browser, signin_metrics::SOURCE_NTP_LINK);
+    chrome::ShowBrowserSignin(browser, signin_metrics::ACCESS_POINT_NTP_LINK);

[Roger Tawa OOO till Jul 10th, 2015/12/02 20:33:48]

I wonder if we need the same logic as above.  I know the old code did not do
that, but it could have been wrong.  Can you check if this is only possible from
ntp?

[gogerald1, 2015/12/03 17:49:03]

Yes, we should check it as above, it is an 'advanced' link in sign in promo
bubble of logn in container of a new page.

 }
 
 void AppLauncherLoginHandler::UpdateLogin() {