Eliminate ash::internal namespace

ash/system/chromeos/brightness/tray_brightness.cc

Index: ash/system/chromeos/brightness/tray_brightness.cc
diff --git a/ash/system/chromeos/brightness/tray_brightness.cc b/ash/system/chromeos/brightness/tray_brightness.cc
index 23f6fa70b34d2c06611d19f66f64244cc20f84f3..901b0aa2a3a4380239c56319a8e1303cae1530f9 100644
--- a/ash/system/chromeos/brightness/tray_brightness.cc
+++ b/ash/system/chromeos/brightness/tray_brightness.cc
@@ -32,10 +32,7 @@
 #include "ui/views/view.h"
 
 namespace ash {
-namespace internal {
-
 namespace tray {
-
 namespace {
 
 // We don't let the screen brightness go lower than this when it's being
@@ -281,5 +278,4 @@ void TrayBrightness::HandleBrightnessChanged(double percent,
     PopupDetailedView(kTrayPopupAutoCloseDelayInSeconds, false);
 }
 
-}  // namespace internal
 }  // namespace ash