Cleanup: Remove unneeded forward declarations from chrome/browser/ui/webui.

chrome/browser/ui/webui/chrome_url_data_manager_backend.h

Index: chrome/browser/ui/webui/chrome_url_data_manager_backend.h
===================================================================
--- chrome/browser/ui/webui/chrome_url_data_manager_backend.h	(revision 109585)
+++ chrome/browser/ui/webui/chrome_url_data_manager_backend.h	(working copy)
@@ -6,21 +6,20 @@
 #define CHROME_BROWSER_UI_WEBUI_CHROME_URL_DATA_MANAGER_BACKEND_H_
 #pragma once
 
+#include <map>
+#include <string>
+#include <vector>
+
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
-#include "base/memory/ref_counted.h"
 #include "base/task.h"
 #include "chrome/browser/ui/webui/chrome_url_data_manager.h"
 #include "net/url_request/url_request_job_factory.h"
 
-#include <map>
-#include <string>
-#include <vector>
-
 class ChromeAppCacheService;
 class ChromeURLDataManagerBackend;
-class FilePath;
 class GURL;
+class RefCountedMemory;
 class URLRequestChromeJob;
 
 namespace net {