Update from chromium https://crrev.com/302282

cc/base/delayed_unique_notifier.h

 // Copyright 2014 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 CC_BASE_DELAYED_UNIQUE_NOTIFIER_H_
 #define CC_BASE_DELAYED_UNIQUE_NOTIFIER_H_
 
 #include "base/callback.h"
 #include "base/memory/weak_ptr.h"
 #include "cc/base/cc_export.h"
@@ skipping 19 matching lines @@
   // Schedule a notification to be run. If another notification is already
   // pending, then it will happen in (at least) given delay from now. That is,
   // if delay is 16ms and a notification has been scheduled 10ms ago (ie, it
   // should trigger in no less than 6ms), then calling schedule will ensure that
   // the only notification that arrives will happen in (at least) 16ms from now.
   void Schedule();
 
   // Cancel any previously scheduled runs.
   void Cancel();
 
+  // Cancel previously scheduled runs and prevent any new runs from starting.
+  // After calling this the DelayedUniqueNotifier will have no outstanding
+  // WeakPtrs.
+  void Shutdown();
+
   // Returns true if a notification is currently scheduled to run.
   bool HasPendingNotification() const;
 
  protected:
   // Virtual for testing.
   virtual base::TimeTicks Now() const;
 
  private:
   void NotifyIfTime();
 
   base::SequencedTaskRunner* task_runner_;
   base::Closure closure_;
   base::TimeDelta delay_;
   base::TimeTicks next_notification_time_;
   bool notification_pending_;
 
   base::WeakPtrFactory<DelayedUniqueNotifier> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(DelayedUniqueNotifier);
 };
 
 }  // namespace cc
 
 #endif  // CC_BASE_DELAYED_UNIQUE_NOTIFIER_H_