Rename Launcher to Shelf.

ash/system/tray/system_tray_item.h

Index: ash/system/tray/system_tray_item.h
diff --git a/ash/system/tray/system_tray_item.h b/ash/system/tray/system_tray_item.h
index b42f3f5b35fde2b42da8a4fa77c144bc573f4190..b0d1284eba6bcdbf26c7352acf290f69e7af4fb4 100644
--- a/ash/system/tray/system_tray_item.h
+++ b/ash/system/tray/system_tray_item.h
@@ -101,9 +101,9 @@ class ASH_EXPORT SystemTrayItem {
   // Returns true if item should hide the arrow.
   virtual bool ShouldHideArrow() const;
 
-  // Returns true if this item needs to force the launcher to be visible when
-  // the launcher is in the auto-hide state. Default is true.
-  virtual bool ShouldShowLauncher() const;
+  // Returns true if this item needs to force the shelf to be visible when
+  // the shelf is in the auto-hide state. Default is true.
+  virtual bool ShouldShowShelf() const;
 
   // Returns the system tray that this item belongs to.
   SystemTray* system_tray() const { return system_tray_; }