[iOS Clean] Added dialogs UI support.

ios/clean/chrome/browser/ui/dialogs/dialog_coordinator.h

Index: ios/clean/chrome/browser/ui/dialogs/dialog_coordinator.h
diff --git a/ios/clean/chrome/browser/ui/dialogs/dialog_coordinator.h b/ios/clean/chrome/browser/ui/dialogs/dialog_coordinator.h
new file mode 100644
index 0000000000000000000000000000000000000000..595f8e15d92822a9bccd8c033299f1546cca4e22
--- /dev/null
+++ b/ios/clean/chrome/browser/ui/dialogs/dialog_coordinator.h
@@ -0,0 +1,19 @@
+// 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_COORDINATOR_H_
+#define IOS_CLEAN_CHROME_BROWSER_UI_DIALOGS_DIALOG_COORDINATOR_H_
+
+#import <Foundation/Foundation.h>
+
+#import "ios/shared/chrome/browser/ui/coordinators/browser_coordinator.h"
+
+// A coordinator that displays dialog UI.  This class is meant to be subclassed,
+// and subclasses are expected to implement the interface in the
+// DialogCoordinator+Subclassing category.  DialogCoordinators support
+// overlaying and are meant to be displayed by OverlayService.
+@interface DialogCoordinator : BrowserCoordinator
+@end
+
+#endif  // IOS_CLEAN_CHROME_BROWSER_UI_DIALOGS_DIALOG_COORDINATOR_H_