chrome: Cleanup class/struct forward declarations

chrome/browser/ui/cocoa/ssl_client_certificate_selector_cocoa.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 CHROME_BROWSER_UI_COCOA_SSL_CLIENT_CERTIFICATE_SELECTOR_COCOA_H_
 #define CHROME_BROWSER_UI_COCOA_SSL_CLIENT_CERTIFICATE_SELECTOR_COCOA_H_
 
 #import <Cocoa/Cocoa.h>
 
 #include <memory>
 #include <vector>
 
 #include "base/mac/scoped_cftyperef.h"
 #include "base/mac/scoped_nsobject.h"
 #include "base/memory/ref_counted.h"
 #include "chrome/browser/ssl/ssl_client_certificate_selector.h"
 #import "chrome/browser/ui/cocoa/constrained_window/constrained_window_custom_sheet.h"
 #import "chrome/browser/ui/cocoa/constrained_window/constrained_window_sheet_controller.h"
 
 namespace content {
 class BrowserContext;
 class ClientCertificateDelegate;
 }
 
+namespace net {
+class X509Certificate;
+}
+
 class ConstrainedWindowMac;
 @class SFChooseIdentityPanel;
 class SSLClientAuthObserverCocoaBridge;
 
 @interface SSLClientCertificateSelectorCocoa
     : NSObject<ConstrainedWindowSheet> {
  @private
   // The list of identities offered to the user.
   base::ScopedCFTypeRef<CFMutableArrayRef> identities_;
   // The corresponding list of certificates.
@@ skipping 22 matching lines @@
                         (std::unique_ptr<content::ClientCertificateDelegate>)
                             delegate;
 - (void)displayForWebContents:(content::WebContents*)webContents;
 - (void)closeWebContentsModalDialog;
 
 - (NSWindow*)overlayWindow;
 
 @end
 
 #endif  // CHROME_BROWSER_UI_COCOA_SSL_CLIENT_CERTIFICATE_SELECTOR_COCOA_H_