[iOS] Upstream code in //ios/chrome/app

ios/chrome/app/deferred_initialization_runner.h

+// Copyright 2012 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_APP_DEFERRED_INITIALIZATION_RUNNER_H_
+#define IOS_CHROME_APP_DEFERRED_INITIALIZATION_RUNNER_H_
+
+#import <Foundation/Foundation.h>
+
+#include "base/ios/block_types.h"
+
+// A singleton object to run initialization code asynchronously. Blocks are
+// scheduled to be run after a delay. The block is named when added to the
+// singleton so that other code can force a deferred block to be run
+// synchronously if necessary.
+@interface DeferredInitializationRunner : NSObject
+
+// Returns singleton instance.
++ (DeferredInitializationRunner*)sharedInstance;
+
+// Schedules |block| to be run after |delaySeconds| on the current queue.
+// This |block| is stored as |name| so code can force this initialization to
+// be run synchronously if necessary. This method may be called more than
+// once with the same |name| parameter. Any block with the same |name|
+// cancels a previously scheduled block of the same |name| if the block has
+// not been run yet.
+- (void)runBlockNamed:(NSString*)name
+                after:(NSTimeInterval)delaySeconds
+                block:(ProceduralBlock)block;
+
+// Looks up a previously scheduled block of |name|. If block has not been
+// run yet, run it synchronously now.
+- (void)runBlockIfNecessary:(NSString*)name;
+
+// Cancels a previously scheduled block of |name|. This is a no-op if the
+// block has already been executed.
+- (void)cancelBlockNamed:(NSString*)name;
+
+@end
+
+#endif  // IOS_CHROME_APP_DEFERRED_INITIALIZATION_RUNNER_H_