ios: Cleanup class/struct forward declarations

ios/chrome/browser/ios_chrome_io_thread.h

 // Copyright 2015 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 IOS_CHROME_BROWSER_IOS_CHROME_IO_THREAD_H_
 #define IOS_CHROME_BROWSER_IOS_CHROME_IO_THREAD_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 11 matching lines @@
 #include "components/prefs/pref_member.h"
 #include "components/ssl_config/ssl_config_service_manager.h"
 #include "ios/web/public/web_thread_delegate.h"
 #include "net/base/network_change_notifier.h"
 #include "net/http/http_network_session.h"
 
 class PrefProxyConfigTracker;
 class PrefService;
 class SystemURLRequestContextGetter;
 
-namespace base {
-class CommandLine;
-}  // namespace base
-
 namespace net {
 class CTPolicyEnforcer;
 class CertVerifier;
 class ChannelIDService;
 class CookieStore;
 class CTVerifier;
 class HostResolver;
 class HttpAuthHandlerFactory;
 class HttpAuthPreferences;
 class HttpServerProperties;
@@ skipping 183 matching lines @@
       system_url_request_context_getter_;
 
   const base::TimeTicks creation_time_;
 
   base::WeakPtrFactory<IOSChromeIOThread> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(IOSChromeIOThread);
 };
 
 #endif  // IOS_CHROME_BROWSER_IOS_CHROME_IO_THREAD_H_