Upstream Chrome on iOS source code [1/11].

ios/chrome/app/application_step.h

+// Copyright 2016 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.
+
+// ======                        New Architecture                         =====
+// =         This code is only used in the new iOS Chrome architecture.       =
+// ============================================================================
+
+#ifndef IOS_CHROME_APP_APPLICATION_STEP_H_
+#define IOS_CHROME_APP_APPLICATION_STEP_H_
+
+#import <Foundation/Foundation.h>
+
+@class ApplicationState;
+
+// Objects that perform application state change steps must conform to this
+// protocol.
+@protocol ApplicationStep<NSObject>
+// Implementors should not modify |state| in -canRunInState.
+- (BOOL)canRunInState:(ApplicationState*)state;
+
+// Implementors should expect to be deallocated after -runInState is called.
+// If an implementor creates objects that need to persist longer than that, they
+// should be stored in |state.state|.
+// Implementors can assume that they are not in any of |state|'s step arrays
+// when this method is called.
+- (void)runInState:(ApplicationState*)state;
+@end
+
+#endif  // IOS_CHROME_APP_APPLICATION_STEP_H_