Simplify LifecycleNotifier and Observer.

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

Index: third_party/WebKit/Source/core/frame/LocalFrameLifecycleNotifier.cpp
diff --git a/third_party/WebKit/Source/core/frame/LocalFrameLifecycleNotifier.cpp b/third_party/WebKit/Source/core/frame/LocalFrameLifecycleNotifier.cpp
index 000ab134d1023629956e368526ab11248872ba74..008e09710fb17f604c1477474412aa34dc9a43fe 100644
--- a/third_party/WebKit/Source/core/frame/LocalFrameLifecycleNotifier.cpp
+++ b/third_party/WebKit/Source/core/frame/LocalFrameLifecycleNotifier.cpp
@@ -11,22 +11,8 @@ 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