ios: Cleanup class/struct forward declarations

ios/chrome/browser/passwords/password_generation_agent.h

 // Copyright 2014 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_PASSWORDS_PASSWORD_GENERATION_AGENT_H_
 #define IOS_CHROME_BROWSER_PASSWORDS_PASSWORD_GENERATION_AGENT_H_
 
 #import <Foundation/Foundation.h>
 #include <vector>
 
 #import "ios/chrome/browser/autofill/form_input_accessory_view_controller.h"
 #import "ios/chrome/browser/passwords/password_generation_offer_view.h"
 #import "ios/chrome/browser/passwords/password_generation_prompt_delegate.h"
 #import "ios/chrome/browser/passwords/passwords_ui_delegate.h"
 #import "ios/web/public/web_state/web_state_observer_bridge.h"
 
 @class CRWWebController;
 @protocol FormInputAccessoryViewProvider;
 @class JsPasswordManager;
 @class JsSuggestionManager;
 
 namespace autofill {
-struct FormData;
 struct FormFieldData;
 struct PasswordForm;
 }
 
 namespace password_manager {
 class PasswordManager;
 class PasswordManagerDriver;
 }
 
 // Performs password generation for a web state. Locates eligible password
@@ skipping 54 matching lines @@
         JSPasswordManager:(JsPasswordManager*)JSPasswordManager
       JSSuggestionManager:(JsSuggestionManager*)JSSuggestionManager
       passwordsUiDelegate:(id<PasswordsUiDelegate>)UIDelegate;
 
 // Clears all per-page state.
 - (void)clearState;
 
 @end
 
 #endif  // IOS_CHROME_BROWSER_PASSWORDS_PASSWORD_GENERATION_AGENT_H_