[iOS Clean] Added dialogs UI support.

ios/clean/chrome/browser/ui/dialogs/dialog_mediator+subclassing.h

+// Copyright 2017 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_CLEAN_CHROME_BROWSER_UI_DIALOGS_DIALOG_MEDIATOR_SUBCLASSING_H_
+#define IOS_CLEAN_CHROME_BROWSER_UI_DIALOGS_DIALOG_MEDIATOR_SUBCLASSING_H_
+
+#import "ios/clean/chrome/browser/ui/dialogs/dialog_mediator.h"
+
+#import "ios/clean/chrome/browser/ui/commands/dialog_commands.h"
+
+@class DialogButtonConfiguration;
+@class DialogTextFieldConfiguration;
+
+// DialogMediator functionality exposed to subclasses.
+@interface DialogMediator (Subclassing)
+
+// The title to provide to the consumer.
+- (NSString*)dialogTitle;
+
+// The message to provide to the consumer.
+- (NSString*)dialogMessage;
+
+// The DialogButtonConfigurations to provide to the consumer.
+- (NSArray<DialogButtonConfiguration*>*)buttonConfigs;
+
+// The DialogTextFieldConfigurations to provide to the consumer.
+- (NSArray<DialogTextFieldConfiguration*>*)textFieldConfigs;
+
+@end
+
+#endif  // IOS_CLEAN_CHROME_BROWSER_UI_DIALOGS_DIALOG_MEDIATOR_SUBCLASSING_H_