Cleanup of removing unnecessary web_contents.h include from webview.h. This is split off from https…

ui/views/controls/webview/webview.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_VIEWS_CONTROLS_WEBVIEW_WEBVIEW_H_
 #define UI_VIEWS_CONTROLS_WEBVIEW_WEBVIEW_H_
 
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
-#include "content/public/browser/web_contents.h"
 #include "content/public/browser/web_contents_delegate.h"
 #include "ui/views/controls/webview/webview_export.h"
 #include "ui/views/view.h"
 
+namespace content {
+class SiteInstance;
+}
+
 namespace views {
 
 class NativeViewHost;
 
 class WEBVIEW_EXPORT WebView : public View,
                                public content::NotificationObserver,
                                public content::WebContentsDelegate {
  public:
   static const char kViewClassName[];
 
@@ skipping 94 matching lines @@
   content::NotificationRegistrar registrar_;
   bool allow_accelerators_;
   gfx::Size preferred_size_;
 
   DISALLOW_COPY_AND_ASSIGN(WebView);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_CONTROLS_WEBVIEW_WEBVIEW_H_