WebUI: prevent WebContent to hold an invalid pointer.

chrome/browser/ui/views/constrained_web_dialog_delegate_views.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/ui/webui/constrained_web_dialog_delegate_base.h"
 
 #include "base/macros.h"
 #include "base/strings/utf_string_conversions.h"
 #include "build/build_config.h"
 #include "chrome/browser/ui/browser_finder.h"
@@ skipping 157 matching lines @@
   // ConstrainedWebDialogDelegate:
   const ui::WebDialogDelegate* GetWebDialogDelegate() const override {
     return impl_->GetWebDialogDelegate();
   }
   ui::WebDialogDelegate* GetWebDialogDelegate() override {
     return impl_->GetWebDialogDelegate();
   }
   void OnDialogCloseFromWebUI() override {
     return impl_->OnDialogCloseFromWebUI();
   }
-  void ReleaseWebContentsOnDialogClose() override {
-    return impl_->ReleaseWebContentsOnDialogClose();
+  std::unique_ptr<content::WebContents> ReleaseWebContents() override {
+    return impl_->ReleaseWebContents();
   }
   gfx::NativeWindow GetNativeDialog() override {
     return impl_->GetNativeDialog();
   }
   content::WebContents* GetWebContents() override {
     return impl_->GetWebContents();
   }
 
   // views::WidgetDelegate:
   views::View* GetInitiallyFocusedView() override { return this; }
@@ skipping 110 matching lines @@
           min_size, max_size);
 
   // For embedded WebContents, use the embedder's WebContents for constrained
   // window.
   content::WebContents* top_level_web_contents =
       constrained_window::GetTopLevelWebContents(web_contents);
   DCHECK(top_level_web_contents);
   constrained_window::CreateWebModalDialogViews(dialog, top_level_web_contents);
   return dialog;
 }