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

cc/base/delayed_unique_notifier.h

Index: cc/base/delayed_unique_notifier.h
diff --git a/cc/base/delayed_unique_notifier.h b/cc/base/delayed_unique_notifier.h
index 59d906bb5f80781d7527e23fffe2c929167e9aa1..02051be7be85b057dbaf388b21c6b2b73df2abb3 100644
--- a/cc/base/delayed_unique_notifier.h
+++ b/cc/base/delayed_unique_notifier.h
@@ -37,6 +37,11 @@ class CC_EXPORT DelayedUniqueNotifier {
   // 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;