Delete obviously unneeded forward declarations in chrome/browser/*.h.

chrome/browser/memory_purger.h

-// Copyright (c) 2009 The Chromium Authors. All rights reserved.
+// Copyright (c) 2010 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.
 
 // MemoryPurger provides static APIs to purge as much memory as possible from
 // all processes.  These can be hooked to various signals to try and balance
 // memory consumption, speed, page swapping, etc.
 
 #ifndef CHROME_BROWSER_MEMORY_PURGER_H_
 #define CHROME_BROWSER_MEMORY_PURGER_H_
 #pragma once
 
 #include "base/basictypes.h"
 
 class RenderProcessHost;
-class SafeBrowsingService;
 
 class MemoryPurger {
  public:
   // Call any of these on the UI thread to purge memory from the named places.
   static void PurgeAll();
   static void PurgeBrowser();
   static void PurgeRenderers();
   static void PurgeRendererForHost(RenderProcessHost* host);
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(MemoryPurger);
 };
 
 #endif  // CHROME_BROWSER_MEMORY_PURGER_H_