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

chrome/browser/ui/gtk/constrained_web_dialog_delegate_gtk.cc

Index: chrome/browser/ui/gtk/constrained_web_dialog_delegate_gtk.cc
diff --git a/chrome/browser/ui/gtk/constrained_web_dialog_delegate_gtk.cc b/chrome/browser/ui/gtk/constrained_web_dialog_delegate_gtk.cc
index 267a832a451b9ffdf17ce27c9ef0ff725206b11c..b21fbffd3e8fb31e1b18c9e7d0bfd386e49d6f79 100644
--- a/chrome/browser/ui/gtk/constrained_web_dialog_delegate_gtk.cc
+++ b/chrome/browser/ui/gtk/constrained_web_dialog_delegate_gtk.cc
@@ -28,10 +28,6 @@ class ConstrainedWebDialogDelegateGtk : public ConstrainedWindowGtkDelegate,
 
   virtual ~ConstrainedWebDialogDelegateGtk() {}
 
-  void set_window(WebContentsModalDialog* dialog) {
-    return impl_->set_window(dialog);
-  }
-
   // ConstrainedWebDialogDelegate interface
   virtual const WebDialogDelegate*
       GetWebDialogDelegate() const OVERRIDE {
@@ -46,8 +42,8 @@ class ConstrainedWebDialogDelegateGtk : public ConstrainedWindowGtkDelegate,
   virtual void ReleaseWebContentsOnDialogClose() OVERRIDE {
     return impl_->ReleaseWebContentsOnDialogClose();
   }
-  virtual WebContentsModalDialog* GetWindow() OVERRIDE {
-    return impl_->GetWindow();
+  virtual gfx::NativeWindow GetNativeWindow() OVERRIDE {
+    return impl_->GetNativeWindow();
   }
   virtual WebContents* GetWebContents() OVERRIDE {
     return impl_->GetWebContents();
@@ -99,8 +95,6 @@ ConstrainedWebDialogDelegate* CreateConstrainedWebDialog(
   ConstrainedWebDialogDelegateGtk* constrained_delegate =
       new ConstrainedWebDialogDelegateGtk(
           browser_context, delegate, tab_delegate);
-  WebContentsModalDialog* web_contents_modal_dialog =
-      new ConstrainedWindowGtk(web_contents, constrained_delegate);
-  constrained_delegate->set_window(web_contents_modal_dialog);
+  new ConstrainedWindowGtk(web_contents, constrained_delegate);
   return constrained_delegate;
 }