ios: Cleanup class/struct forward declarations

ios/chrome/browser/passwords/js_credential_manager.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_PASSWORDS_JS_CREDENTIAL_MANAGER_H_
 #define IOS_CHROME_BROWSER_PASSWORDS_JS_CREDENTIAL_MANAGER_H_
 
 #include "ios/web/public/web_state/credential.h"
 #import "ios/web/public/web_state/js/crw_js_injection_manager.h"
 
-namespace base {
-class DictionaryValue;
-}  // namespace base
-
 // Constants for rejecting requests.
 extern const char kCredentialsPendingRequestErrorType[];
 extern const char kCredentialsPendingRequestErrorMessage[];
 extern const char kCredentialsSecurityErrorType[];
 extern const char kCredentialsPasswordStoreUnavailableErrorType[];
 extern const char kCredentialsPasswordStoreUnavailableErrorMessage[];
 extern const char kCredentialsSecurityErrorMessageUntrustedOrigin[];
 
 // Injects the JavaScript that implements the request credentials API and
 // provides an app-side interface for interacting with it.
@@ skipping 16 matching lines @@
 // the specified |errorType| and |message|. |completionHandler| will be invoked
 // after the operation has completed with YES if successful.
 - (void)rejectPromiseWithRequestID:(NSInteger)requestID
                          errorType:(NSString*)errorType
                            message:(NSString*)message
                  completionHandler:(void (^)(BOOL))completionHandler;
 
 @end
 
 #endif  // IOS_CHROME_BROWSER_PASSWORDS_JS_CREDENTIAL_MANAGER_H_