Added Ash.SystemMenu.DefaultView.VisibleRows histogram.

ash/system/chromeos/media_security/multi_profile_media_tray_item.cc

Index: ash/system/chromeos/media_security/multi_profile_media_tray_item.cc
diff --git a/ash/system/chromeos/media_security/multi_profile_media_tray_item.cc b/ash/system/chromeos/media_security/multi_profile_media_tray_item.cc
index 02b7103ce57c02015a1b5f4a3c0358b0654cbfea..3dc6664dd08e1ef7c420bbc612d21c7906a38f7e 100644
--- a/ash/system/chromeos/media_security/multi_profile_media_tray_item.cc
+++ b/ash/system/chromeos/media_security/multi_profile_media_tray_item.cc
@@ -62,7 +62,8 @@ class MultiProfileMediaTrayView : public TrayItemView,
 }  // namespace tray
 
 MultiProfileMediaTrayItem::MultiProfileMediaTrayItem(SystemTray* system_tray)
-    : SystemTrayItem(system_tray), tray_view_(NULL) {}
+    : SystemTrayItem(system_tray, UMA_MULTI_PROFILE_MEDIA),
+      tray_view_(nullptr) {}
 
 MultiProfileMediaTrayItem::~MultiProfileMediaTrayItem() {}