Add dialog-specific styling, restore old-style task manager.

ui/views/window/dialog_delegate.h

Index: ui/views/window/dialog_delegate.h
diff --git a/ui/views/window/dialog_delegate.h b/ui/views/window/dialog_delegate.h
index 401456ea646ebd7cbf33b9d8cfe97ddfd83a9345..958707c2fd0c92e491798bd0d8a361aecf2b0ff7 100644
--- a/ui/views/window/dialog_delegate.h
+++ b/ui/views/window/dialog_delegate.h
@@ -31,7 +31,8 @@ class VIEWS_EXPORT DialogDelegate : public ui::DialogModel,
  public:
   virtual ~DialogDelegate();
 
-  // Returns whether to use the new dialog style.
+  // Returns whether to use the new dialog style in general.
+  // See UseNewStyleForThisDialog() for dialog-specific styling.
   static bool UseNewStyle();
 
   // Create a |dialog| window Widget with the specified |context| or |parent|.
@@ -96,6 +97,9 @@ class VIEWS_EXPORT DialogDelegate : public ui::DialogModel,
   static NonClientFrameView* CreateNewStyleFrameView(Widget* widget,
                                                      bool force_opaque_border);
 
+  // Returns whether this particular dialog should use the new dialog style.
+  virtual bool UseNewStyleForThisDialog() const;
+
   // Called when the window has been closed.
   virtual void OnClose() {}