content: Cleanup class/struct forward declarations

ui/web_dialogs/web_dialog_web_contents_delegate.h

 // 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.
 
 #ifndef UI_WEB_DIALOGS_WEB_DIALOG_WEB_CONTENTS_DELEGATE_H_
 #define UI_WEB_DIALOGS_WEB_DIALOG_WEB_CONTENTS_DELEGATE_H_
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "content/public/browser/web_contents_delegate.h"
 #include "ui/web_dialogs/web_dialogs_export.h"
 
+namespace content {
+class BrowserContext;
+}
+
 namespace ui {
 
 // This class implements (and mostly ignores) most of
 // content::WebContentsDelegate for use in a Web dialog. Subclasses need only
 // override a few methods instead of the everything from
 // content::WebContentsDelegate; this way, implementations on all platforms
 // behave consistently.
 class WEB_DIALOGS_EXPORT WebDialogWebContentsDelegate
     : public content::WebContentsDelegate {
  public:
@@ skipping 49 matching lines @@
   content::BrowserContext* browser_context_;
 
   std::unique_ptr<WebContentsHandler> handler_;
 
   DISALLOW_COPY_AND_ASSIGN(WebDialogWebContentsDelegate);
 };
 
 }  // namespace ui
 
 #endif  // UI_WEB_DIALOGS_WEB_DIALOG_WEB_CONTENTS_DELEGATE_H_