Eliminate ash::internal namespace

ash/system/chromeos/tray_tracing.h

Index: ash/system/chromeos/tray_tracing.h
diff --git a/ash/system/chromeos/tray_tracing.h b/ash/system/chromeos/tray_tracing.h
index f9491e1d90319dd1595a15eba32f8527545d94ff..683b326cbc17344c558d96c4ea724e5f42ed83b6 100644
--- a/ash/system/chromeos/tray_tracing.h
+++ b/ash/system/chromeos/tray_tracing.h
@@ -22,8 +22,6 @@ class ASH_EXPORT TracingObserver {
   virtual void OnTracingModeChanged(bool value) = 0;
 };
 
-namespace internal {
-
 // This is the item that displays when users enable performance tracing at
 // chrome://slow.  It alerts them that this mode is running, and provides an
 // easy way to open the page to disable it.
@@ -51,7 +49,6 @@ class TrayTracing : public TrayImageItem,
   DISALLOW_COPY_AND_ASSIGN(TrayTracing);
 };
 
-}  // namespace internal
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_TRAY_TRACING_H_