Use ChildFrameDisconnector when detaching child frames of a LocalFrame.

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

Index: third_party/WebKit/Source/core/frame/LocalFrame.cpp
diff --git a/third_party/WebKit/Source/core/frame/LocalFrame.cpp b/third_party/WebKit/Source/core/frame/LocalFrame.cpp
index 1115a09eebaf013b338e8bf577c68c0ecf6c5e25..8c9fb0d931e68880b7fbc57cad647ae04aa4d157 100644
--- a/third_party/WebKit/Source/core/frame/LocalFrame.cpp
+++ b/third_party/WebKit/Source/core/frame/LocalFrame.cpp
@@ -31,6 +31,7 @@
 
 #include "bindings/core/v8/ScriptController.h"
 #include "core/InstrumentingAgents.h"
+#include "core/dom/ChildFrameDisconnector.h"
 #include "core/dom/DocumentType.h"
 #include "core/dom/StyleChangeReason.h"
 #include "core/editing/EditingUtilities.h"
@@ -461,6 +462,14 @@ bool LocalFrame::shouldClose()
     return m_loader.shouldClose();
 }
 
+void LocalFrame::detachChildren()
+{
+    DCHECK(m_loader.stateMachine()->creatingInitialEmptyDocument() || document());
+
+    if (Document* document = this->document())
+        ChildFrameDisconnector(*document).disconnect();
+}
+
 void LocalFrame::setDOMWindow(LocalDOMWindow* domWindow)
 {
     // Oilpan: setDOMWindow() cannot be used when finalizing. Which