Simplify LifecycleNotifier and Observer.

third_party/WebKit/Source/core/frame/LocalFrameLifecycleNotifier.cpp

 // Copyright 2015 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.
 
 #include "core/frame/LocalFrameLifecycleNotifier.h"
 
 #include "core/frame/LocalFrameLifecycleObserver.h"
 
 namespace blink {
 
 void LocalFrameLifecycleNotifier::notifyWillDetachFrameHost()
 {
     TemporaryChange<IterationType> scope(m_iterating, IteratingOverAll);
-#if !ENABLE(OILPAN)
-    // Notifications perform unknown amounts of heap allocations,
-    // which might trigger (conservative) GCs. This will flush out
-    // dead observers, causing the _non-heap_ set be updated. Snapshot
-    // the observers and explicitly check if they're still alive before
-    // notifying.
-    Vector<RawPtr<LocalFrameLifecycleObserver>> snapshotOfObservers;
-    copyToVector(m_observers, snapshotOfObservers);
-    for (LocalFrameLifecycleObserver* observer : snapshotOfObservers) {
-        if (m_observers.contains(observer))
-            observer->willDetachFrameHost();
-    }
-#else
     for (LocalFrameLifecycleObserver* observer : m_observers)
         observer->willDetachFrameHost();
-#endif
 }
 
 } // namespace blink