Refactor ViewsDelegate singleton

ui/views/widget/widget_delegate.cc

Index: ui/views/widget/widget_delegate.cc
diff --git a/ui/views/widget/widget_delegate.cc b/ui/views/widget/widget_delegate.cc
index f37c4368a765e7e4c12bcaaa10669aca1fa05f74..e62aa92847e67feb742e9451dda687b6fd920ac3 100644
--- a/ui/views/widget/widget_delegate.cc
+++ b/ui/views/widget/widget_delegate.cc
@@ -116,11 +116,11 @@ std::string WidgetDelegate::GetWindowName() const {
 void WidgetDelegate::SaveWindowPlacement(const gfx::Rect& bounds,
                                          ui::WindowShowState show_state) {
   std::string window_name = GetWindowName();
-  if (!ViewsDelegate::views_delegate || window_name.empty())
+  if (!ViewsDelegate::GetInstance() || window_name.empty())
     return;
 
-  ViewsDelegate::views_delegate->SaveWindowPlacement(
-      GetWidget(), window_name, bounds, show_state);
+  ViewsDelegate::GetInstance()->SaveWindowPlacement(GetWidget(), window_name,
+                                                    bounds, show_state);
 }
 
 bool WidgetDelegate::GetSavedWindowPlacement(
@@ -128,10 +128,10 @@ bool WidgetDelegate::GetSavedWindowPlacement(
     gfx::Rect* bounds,
     ui::WindowShowState* show_state) const {
   std::string window_name = GetWindowName();
-  if (!ViewsDelegate::views_delegate || window_name.empty())
+  if (!ViewsDelegate::GetInstance() || window_name.empty())
     return false;
 
-  return ViewsDelegate::views_delegate->GetSavedWindowPlacement(
+  return ViewsDelegate::GetInstance()->GetSavedWindowPlacement(
       widget, window_name, bounds, show_state);
 }