content: Cleanup class/struct forward declarations

content/test/test_web_contents.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 CONTENT_TEST_TEST_WEB_CONTENTS_H_
 #define CONTENT_TEST_TEST_WEB_CONTENTS_H_
 
 #include <stdint.h>
 
 #include <string>
 
 #include "content/browser/web_contents/web_contents_impl.h"
 #include "content/public/test/web_contents_tester.h"
 #include "content/test/test_render_frame_host.h"
 #include "content/test/test_render_view_host.h"
 #include "ui/base/page_transition_types.h"
 
 class GURL;
 class Referrer;
-class SiteInstanceImpl;
 
 namespace content {
 
 class NavigationData;
 class NavigationHandle;
 class RenderViewHost;
 class TestRenderViewHost;
 class WebContentsTester;
 
 // Subclass WebContentsImpl to ensure it creates TestRenderViewHosts
@@ skipping 120 matching lines @@
   // Expectations for arguments of |SetHistoryOffsetAndLength()|.
   bool expect_set_history_offset_and_length_;
   int expect_set_history_offset_and_length_history_offset_;
   int expect_set_history_offset_and_length_history_length_;
   std::string save_frame_headers_;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_TEST_TEST_WEB_CONTENTS_H_