Cleanup: Remove unneeded forward declarations from various chrome/browser subdirectories.

chrome/browser/safe_browsing/download_protection_service.h

Index: chrome/browser/safe_browsing/download_protection_service.h
===================================================================
--- chrome/browser/safe_browsing/download_protection_service.h	(revision 109953)
+++ chrome/browser/safe_browsing/download_protection_service.h	(working copy)
@@ -20,12 +20,12 @@
 #include "base/memory/ref_counted.h"
 #include "googleurl/src/gurl.h"
 
+class DownloadItem;
+class SafeBrowsingService;
+
 namespace net {
 class URLRequestContextGetter;
-class URLRequestStatus;
 }  // namespace net
-class DownloadItem;
-class SafeBrowsingService;
 
 namespace safe_browsing {
 class SignatureUtil;