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

components/signin/core/browser/signin_metrics.h

Index: components/signin/core/browser/signin_metrics.h
diff --git a/components/signin/core/browser/signin_metrics.h b/components/signin/core/browser/signin_metrics.h
index fa7242bfd4de44e57ef0118fb6cdf77e7ca6dcc4..958fa0bc0cba993cbecc65b74d4d17673ce8852d 100644
--- a/components/signin/core/browser/signin_metrics.h
+++ b/components/signin/core/browser/signin_metrics.h
@@ -98,22 +98,50 @@ enum {
   HISTOGRAM_CONFIRM_MAX
 };
 
-// Enum valus used with the "Signin.SigninSource" histogram, which tracks the
-// source that launched a Gaia signin page.
+// TODO(gogerald): right now, gaia server needs to distinguish the source from
+// signin_metrics::SOURCE_START_PAGE, signin_metrics::SOURCE_SETTINGS and the
+// others to show advanced sync setting, remove them after switching to Minute
+// Maid sign in flow.
+// This was previously used in Signin.SigninSource UMA histogram, but no longer
+// used after having below AccessPoint and Reason related histograms.
 enum Source {
-  SOURCE_START_PAGE = 0, // This must be first.
-  SOURCE_NTP_LINK,
-  SOURCE_MENU,
-  SOURCE_SETTINGS,
-  SOURCE_EXTENSION_INSTALL_BUBBLE,
-  SOURCE_APP_LAUNCHER,
-  SOURCE_APPS_PAGE_LINK,
-  SOURCE_BOOKMARK_BUBBLE,
-  SOURCE_AVATAR_BUBBLE_SIGN_IN,
-  SOURCE_AVATAR_BUBBLE_ADD_ACCOUNT,
-  SOURCE_DEVICES_PAGE,
-  SOURCE_REAUTH,
-  SOURCE_UNKNOWN, // This must be last.
+  SOURCE_START_PAGE = 0,  // This must be first.
+  SOURCE_SETTINGS = 3,
+  SOURCE_OTHERS = 13,
+};
+
+// Enum values which enumerates all access points where sign in could be
+// initiated. Not all of them exist on all platforms. They are used with
+// "Signin.SigninStartedAccessPoint" and "Signin.SigninCompletedAccessPoint"
+// histograms.
+enum class AccessPoint : int {
+  ACCESS_POINT_START_PAGE = 0,
+  ACCESS_POINT_NTP_LINK,
+  ACCESS_POINT_MENU,
+  ACCESS_POINT_SETTINGS,
+  ACCESS_POINT_SUPERVISED_USER,
+  ACCESS_POINT_EXTENSION_INSTALL_BUBBLE,
+  ACCESS_POINT_EXTENSIONS,
+  ACCESS_POINT_APPS_PAGE_LINK,
+  ACCESS_POINT_BOOKMARK_BUBBLE,
+  ACCESS_POINT_BOOKMARK_MANAGER,
+  ACCESS_POINT_AVATAR_BUBBLE_SIGN_IN,
+  ACCESS_POINT_USER_MANAGER,
+  ACCESS_POINT_DEVICES_PAGE,
+  ACCESS_POINT_CLOUD_PRINT,
+  ACCESS_POINT_CONTENT_AREA,
+  ACCESS_POINT_SIGNIN_PROMO,
+  ACCESS_POINT_RECENT_TABS,
+  ACCESS_POINT_MAX  // This must be last.
+};
+
+// Enum values which enumerates all reasons to start sign in process.
+enum class Reason : int {
+  REASON_SIGNIN_PRIMARY_ACCOUNT = 0,
+  REASON_ADD_SECONDARY_ACCOUNT,
+  REASON_REAUTHENTICATION,
+  REASON_UNLOCK,
+  REASON_MAX  // This must be last.
 };
 
 // Enum values used for use with the "Signin.Reauth" histogram.
@@ -177,6 +205,13 @@ enum AccountReconcilorState {
   ACCOUNT_RECONCILOR_HISTOGRAM_COUNT,
 };
 
+// Tracks the access point of sign in.
+void LogSigninAccessPointStarted(AccessPoint access_point);
+void LogSigninAccessPointCompleted(AccessPoint access_point);
+
+// Tracks the reason of sign in.
+void LogSigninReason(Reason reason);
+
 // Log to UMA histograms and UserCounts stats about a single execution of the
 // AccountReconciler.
 // |total_number_accounts| - How many accounts are in the browser for this
@@ -207,9 +242,6 @@ void LogSigninAccountReconciliationDuration(base::TimeDelta duration,
 // Track a successful signin.
 void LogSigninAddAccount();
 
-// Tracks the original source that showed the signin page.
-void LogSigninSource(Source source);
-
 // Track a successful signin of a profile.
 void LogSigninProfile(bool is_first_run, base::Time install_date);