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

chrome/browser/tab_contents/simple_alert_infobar_delegate.h

 // Copyright (c) 2011 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 CHROME_BROWSER_TAB_CONTENTS_SIMPLE_ALERT_INFOBAR_DELEGATE_H_
 #define CHROME_BROWSER_TAB_CONTENTS_SIMPLE_ALERT_INFOBAR_DELEGATE_H_
 #pragma once
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/string16.h"
 #include "chrome/browser/tab_contents/confirm_infobar_delegate.h"
 
-class SkBitmap;
-class TabContents;
-
 class SimpleAlertInfoBarDelegate : public ConfirmInfoBarDelegate {
  public:
   SimpleAlertInfoBarDelegate(InfoBarTabHelper* infobar_helper,
                              gfx::Image* icon,  // May be NULL.
                              const string16& message,
                              bool auto_expire);
 
  private:
   virtual ~SimpleAlertInfoBarDelegate();
 
   // ConfirmInfoBarDelegate:
   virtual bool ShouldExpire(
       const content::LoadCommittedDetails& details) const OVERRIDE;
   virtual gfx::Image* GetIcon() const OVERRIDE;
   virtual string16 GetMessageText() const OVERRIDE;
   virtual int GetButtons() const OVERRIDE;
 
   gfx::Image* icon_;
   string16 message_;
   bool auto_expire_;  // Should it expire automatically on navigation?
 
   DISALLOW_COPY_AND_ASSIGN(SimpleAlertInfoBarDelegate);
 };
 
 #endif  // CHROME_BROWSER_TAB_CONTENTS_SIMPLE_ALERT_INFOBAR_DELEGATE_H_