Factor out uses of the WebContentsModalDialog interface from platform-independent code

chrome/browser/ui/webui/constrained_web_dialog_ui.h

Index: chrome/browser/ui/webui/constrained_web_dialog_ui.h
diff --git a/chrome/browser/ui/webui/constrained_web_dialog_ui.h b/chrome/browser/ui/webui/constrained_web_dialog_ui.h
index 791e0bf4fc8e74a12940f16a2372513bd4534a44..f0855d414d6f98bbf56d8af6dad0c1f5149b5b23 100644
--- a/chrome/browser/ui/webui/constrained_web_dialog_ui.h
+++ b/chrome/browser/ui/webui/constrained_web_dialog_ui.h
@@ -6,9 +6,9 @@
 #define CHROME_BROWSER_UI_WEBUI_CONSTRAINED_WEB_DIALOG_UI_H_
 
 #include "base/compiler_specific.h"
+#include "chrome/browser/ui/native_web_contents_modal_dialog.h"
 #include "content/public/browser/web_ui_controller.h"
-
-class WebContentsModalDialog;
+#include "ui/gfx/native_widget_types.h"
 
 namespace content {
 class BrowserContext;
@@ -35,12 +35,12 @@ class ConstrainedWebDialogDelegate {
   // released WebContents.
   virtual void ReleaseWebContentsOnDialogClose() = 0;
 
-  // Returns the WebContentsModalDialog.
-  virtual WebContentsModalDialog* GetWindow() = 0;
-
   // Returns the WebContents owned by the constrained window.
   virtual content::WebContents* GetWebContents() = 0;
 
+  // Returns the native type used to display the dialog.
+  virtual NativeWebContentsModalDialog GetNativeDialog() = 0;
+
  protected:
   virtual ~ConstrainedWebDialogDelegate() {}
 };