Rewrite scoped_ptr<T>(NULL) to use the default ctor in ash/.

ash/wm/frame_painter.cc

Index: ash/wm/frame_painter.cc
diff --git a/ash/wm/frame_painter.cc b/ash/wm/frame_painter.cc
index bcb535267138d3cf41ebfaf2fb6da2b9ed6c14c8..712594fead81bdfaf01a592e4ecfdb58a7d050d3 100644
--- a/ash/wm/frame_painter.cc
+++ b/ash/wm/frame_painter.cc
@@ -230,9 +230,7 @@ FramePainter::FramePainter()
       crossfade_theme_frame_id_(0),
       crossfade_theme_frame_overlay_id_(0),
       crossfade_opacity_(0),
-      crossfade_animation_(NULL),
-      size_button_behavior_(SIZE_BUTTON_MAXIMIZES) {
-}
+      size_button_behavior_(SIZE_BUTTON_MAXIMIZES) {}
 
 FramePainter::~FramePainter() {
   // Sometimes we are destroyed before the window closes, so ensure we clean up.