Record shutdown type UMA

chrome/browser/browser_shutdown.h

Index: chrome/browser/browser_shutdown.h
diff --git a/chrome/browser/browser_shutdown.h b/chrome/browser/browser_shutdown.h
index e3cf6506841d13a1bcdb9817be6c1a14c77dda57..0e239b4783a44a09bb050f51fb433a0706ebd4b7 100644
--- a/chrome/browser/browser_shutdown.h
+++ b/chrome/browser/browser_shutdown.h
@@ -33,7 +33,9 @@ enum ShutdownType {
   // user clicked on the Exit menu item
   BROWSER_EXIT,
   // windows is logging off or shutting down
-  END_SESSION
+  END_SESSION,
+  // This value should always be the last element of this enum.
+  SHUTDOWN_TYPE_MAX_VALUE,

[sky, 2016/09/09 15:40:56]

I'm not a fan of this style. It means the enum has a fake value that isn't
legal, yet has to be dealt with in switch statements because it's defined. How
about a constant instead?

constexpr kMaxShutdownValue = static_cast<int>(END_SESSION) + 1;?

[hashimoto, 2016/09/12 05:10:18]

Sounds good.
Done.

 };
 
 void RegisterPrefs(PrefRegistrySimple* registry);