Declaring the weak_ptr_factory in proper order.

ash/system/chromeos/brightness/tray_brightness.h

Index: ash/system/chromeos/brightness/tray_brightness.h
diff --git a/ash/system/chromeos/brightness/tray_brightness.h b/ash/system/chromeos/brightness/tray_brightness.h
index 379a8d2e109205d5766b149cf9977a6cf64fd1ea..1c0d10d418b74362510bf65ceee0daeffeac8aeb 100644
--- a/ash/system/chromeos/brightness/tray_brightness.h
+++ b/ash/system/chromeos/brightness/tray_brightness.h
@@ -50,8 +50,6 @@ class ASH_EXPORT TrayBrightness
 
   void HandleBrightnessChanged(double percent, bool user_initiated);
 
-  base::WeakPtrFactory<TrayBrightness> weak_ptr_factory_;
-
   tray::BrightnessView* brightness_view_;
 
   // Brightness level in the range [0.0, 100.0] that we've heard about most
@@ -61,6 +59,8 @@ class ASH_EXPORT TrayBrightness
   // Has |current_percent_| been initialized?
   bool got_current_percent_;
 
+  base::WeakPtrFactory<TrayBrightness> weak_ptr_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(TrayBrightness);
 };