Simplify handling of LocalFrame lifecycle notifications.

Source/core/frame/LocalFrameLifecycleNotifier.cpp

Index: Source/core/frame/LocalFrameLifecycleNotifier.cpp
diff --git a/Source/core/frame/LocalFrameLifecycleNotifier.cpp b/Source/core/frame/LocalFrameLifecycleNotifier.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..e7a9174694128c2022738a15f2bbef83bc703c99
--- /dev/null
+++ b/Source/core/frame/LocalFrameLifecycleNotifier.cpp
@@ -0,0 +1,19 @@
+// 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 "config.h"
+#include "core/frame/LocalFrameLifecycleNotifier.h"
+
+#include "core/frame/FrameDestructionObserver.h"
+
+namespace blink {
+
+void LocalFrameLifecycleNotifier::notifyWillDetachFrameHost()
+{
+    TemporaryChange<IterationType> scope(m_iterating, IteratingOverAll);
+    for (FrameDestructionObserver* observer : m_observers)
+        observer->willDetachFrameHost();
+}
+
+} // namespace blink