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

ash/shelf/shelf_widget.cc

Index: ash/shelf/shelf_widget.cc
diff --git a/ash/shelf/shelf_widget.cc b/ash/shelf/shelf_widget.cc
index f789eac777f766ad4b30c292e0ab477398b35b77..9f959467f9ce846278ce0290b9d57f4cdd678eee 100644
--- a/ash/shelf/shelf_widget.cc
+++ b/ash/shelf/shelf_widget.cc
@@ -427,15 +427,13 @@ void ShelfWidget::DelegateView::UpdateBackground(int alpha) {
   SchedulePaint();
 }
 
-ShelfWidget::ShelfWidget(
-    aura::Window* shelf_container,
-    aura::Window* status_container,
-    internal::WorkspaceController* workspace_controller) :
-    launcher_(NULL),
-    delegate_view_(new DelegateView(this)),
-    background_animator_(delegate_view_, 0, kLauncherBackgroundAlpha),
-    activating_as_fallback_(false),
-    window_container_(shelf_container) {
+ShelfWidget::ShelfWidget(aura::Window* shelf_container,
+                         aura::Window* status_container,
+                         internal::WorkspaceController* workspace_controller)
+    : delegate_view_(new DelegateView(this)),
+      background_animator_(delegate_view_, 0, kLauncherBackgroundAlpha),
+      activating_as_fallback_(false),
+      window_container_(shelf_container) {
   views::Widget::InitParams params(
       views::Widget::InitParams::TYPE_WINDOW_FRAMELESS);
   params.transparent = true;