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

components/signin/core/browser/signin_metrics.cc

Index: components/signin/core/browser/signin_metrics.cc
diff --git a/components/signin/core/browser/signin_metrics.cc b/components/signin/core/browser/signin_metrics.cc
index a154d1105b81bd9751a26219a581780ad109a0bd..e0fe72c6d90268be129fba583efbfe877d8b5105 100644
--- a/components/signin/core/browser/signin_metrics.cc
+++ b/components/signin/core/browser/signin_metrics.cc
@@ -21,6 +21,23 @@ DifferentPrimaryAccounts ComparePrimaryAccounts(bool primary_accounts_same,
   return COOKIE_AND_TOKEN_PRIMARIES_DIFFERENT;
 }
 
+void LogSigninAccessPointStarted(AccessPoint access_point) {
+  UMA_HISTOGRAM_ENUMERATION("Signin.SigninStartedAccessPoint",
+                            static_cast<int>(access_point),
+                            static_cast<int>(AccessPoint::ACCESS_POINT_MAX));
+}
+
+void LogSigninAccessPointCompleted(AccessPoint access_point) {
+  UMA_HISTOGRAM_ENUMERATION("Signin.SigninCompletedAccessPoint",
+                            static_cast<int>(access_point),
+                            static_cast<int>(AccessPoint::ACCESS_POINT_MAX));
+}
+
+void LogSigninReason(Reason reason) {
+  UMA_HISTOGRAM_ENUMERATION("Signin.SigninReason", static_cast<int>(reason),

[Alexei Svitkine (slow), 2015/12/04 20:58:15]

Please document this in histograms.xml.

[gogerald1, 2015/12/05 00:06:13]

Done.

+                            static_cast<int>(Reason::REASON_MAX));
+}
+
 void LogSigninAccountReconciliation(int total_number_accounts,
                                     int count_added_to_cookie_jar,
                                     int count_removed_from_cookie_jar,
@@ -73,10 +90,6 @@ void LogSigninProfile(bool is_first_run, base::Time install_date) {
                        elapsed_time.InMinutes());
 }
 
-void LogSigninSource(Source source) {
-  UMA_HISTOGRAM_ENUMERATION("Signin.SigninSource", source, HISTOGRAM_MAX);
-}
-
 void LogSigninAddAccount() {
   // Account signin may fail for a wide variety of reasons. There is no
   // explicit false, but one can compare this value with the various UI