[iOS Clean] Added dialogs UI support.

ios/clean/chrome/browser/ui/dialogs/dialog_consumer.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_CONSUMER_H_
+#define IOS_CLEAN_CHROME_BROWSER_UI_DIALOGS_DIALOG_CONSUMER_H_
+
+#import <Foundation/Foundation.h>
+
+@class DialogButtonItem;
+@class DialogTextFieldItem;
+
+// A DialogConsumer uses data provided by this protocol to configure and run a
+// dialog.

[marq (ping after 24h), 2017/06/14 10:52:15]

Document what the expectations are around calling these methods on a consumer
more than once. 

[kkhorimoto, 2017/06/23 06:24:18]

Done.

+@protocol DialogConsumer<NSObject>
+
+// Sets the title of the dialog.
+- (void)setDialogTitle:(NSString*)title;
+
+// Sets the message of the dialog.
+- (void)setDialogMessage:(NSString*)message;
+
+// Sets the button items to display in the dialog.
+- (void)setDialogButtonItems:(NSArray<DialogButtonItem*>*)buttonItems;
+
+// Sets the text field items to display in the dialog.
+- (void)setDialogTextFieldItems:(NSArray<DialogTextFieldItem*>*)textFieldItems;
+
+@end
+
+#endif  // IOS_CLEAN_CHROME_BROWSER_UI_DIALOGS_DIALOG_CONSUMER_H_