Added Ash.SystemMenu.DefaultView.VisibleItems histogram.

ash/common/system/tray/system_tray_item.h

Index: ash/common/system/tray/system_tray_item.h
diff --git a/ash/common/system/tray/system_tray_item.h b/ash/common/system/tray/system_tray_item.h
index 09c5f82d7112e85599fcfc318b4d4bdf1fca17f6..4925f6a81c67cf2349d5711568f196270ea7ad16 100644
--- a/ash/common/system/tray/system_tray_item.h
+++ b/ash/common/system/tray/system_tray_item.h
@@ -16,11 +16,48 @@ class View;
 
 namespace ash {
 class SystemTray;
+class SystemTrayBubble;
 class TrayItemView;
 
 class ASH_EXPORT SystemTrayItem {
  public:
-  explicit SystemTrayItem(SystemTray* system_tray);
+  // The different types of SystemTrayItems.
+  //
+  // NOTE: These values are used for UMA metrics so do NOT re-order this enum
+  // and only insert items before the COUNT item.
+  enum UmaType {
+    // SystemTrayItem's with this type are not recorded in the histogram.
+    UMA_NOT_RECORDED = 0,
+    // Used for testing purposes only.
+    UMA_TEST = 1,
+    UMA_ACCESSIBILITY = 2,
+    UMA_AUDIO = 3,
+    UMA_BLUETOOTH = 4,
+    UMA_CAPS_LOCK = 5,
+    UMA_CAST = 6,
+    UMA_DATE = 7,
+    UMA_DISPLAY = 8,
+    UMA_DISPLAY_BRIGHTNESS = 9,
+    UMA_ENTERPRISE = 10,
+    UMA_IME = 11,
+    UMA_MULTI_PROFILE_MEDIA = 12,
+    UMA_NETWORK = 13,
+    UMA_SETTINGS = 14,
+    UMA_UPDATE = 15,
+    UMA_POWER = 16,
+    UMA_ROTATION_LOCK = 17,
+    UMA_SCREEN_CAPTURE = 18,
+    UMA_SCREEN_SHARE = 19,
+    UMA_SESSION_LENGTH_LIMIT = 20,
+    UMA_SMS = 21,
+    UMA_SUPERVISED_USER = 22,
+    UMA_TRACING = 23,
+    UMA_USER = 24,
+    UMA_VPN = 25,
+    UMA_COUNT = 26,
+  };
+
+  SystemTrayItem(SystemTray* system_tray, UmaType type);
   virtual ~SystemTrayItem();
 
   // Create* functions may return NULL if nothing should be displayed for the
@@ -107,7 +144,13 @@ class ASH_EXPORT SystemTrayItem {
   void set_restore_focus(bool restore_focus) { restore_focus_ = restore_focus; }
 
  private:
+  // Accesses uma_type().
+  friend class SystemTrayBubble;
+
+  UmaType uma_type() const { return uma_type_; }
+
   SystemTray* system_tray_;
+  UmaType uma_type_;
   bool restore_focus_;
 
   DISALLOW_COPY_AND_ASSIGN(SystemTrayItem);