Detach old frame on WebFrame::swap.

Source/core/frame/RemoteFrame.cpp

 // Copyright 2014 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/RemoteFrame.h"
 
 #include "bindings/core/v8/WindowProxy.h"
 #include "bindings/core/v8/WindowProxyManager.h"
 #include "core/dom/RemoteSecurityContext.h"
@@ skipping 65 matching lines @@
 {
     UserGestureStatus gesture = UserGestureIndicator::processingUserGesture() ? UserGestureStatus::Active : UserGestureStatus::None;
     navigate(*passedRequest.originDocument(), passedRequest.resourceRequest().url(), passedRequest.lockBackForwardList(), gesture);
 }
 
 void RemoteFrame::reload(FrameLoadType frameLoadType, ClientRedirectPolicy clientRedirectPolicy)
 {
     remoteFrameClient()->reload(frameLoadType, clientRedirectPolicy);
 }
 
-void RemoteFrame::detach()
+void RemoteFrame::detach(FrameDetachType type)
 {
     PluginScriptForbiddenScope forbidPluginDestructorScripting;
     // Frame::detach() requires the caller to keep a reference to this, since
     // otherwise it may clear the last reference to this, causing it to be
     // deleted, which can cause a use-after-free.
     RefPtrWillBeRawPtr<RemoteFrame> protect(this);
     detachChildren();
     if (!client())
         return;
     client()->willBeDetached();
     m_windowProxyManager->clearForClose();
     setView(nullptr);
-    Frame::detach();
+    Frame::detach(type);
+}
+
+bool RemoteFrame::prepareForCommit()
+{
+    detachChildren();
+    return !!host();
 }
 
 RemoteSecurityContext* RemoteFrame::securityContext() const
 {
     return m_securityContext.get();
 }
 
 void RemoteFrame::disconnectOwnerElement()
 {
     // The RemotePlatformLayer needs to be cleared in disconnectOwnerElement()
@@ skipping 55 matching lines @@
     if (m_remotePlatformLayer)
         GraphicsLayer::registerContentsLayer(layer);
 
     ASSERT(owner());
     toHTMLFrameOwnerElement(owner())->setNeedsCompositingUpdate();
     if (LayoutPart* layoutObject = ownerLayoutObject())
         layoutObject->layer()->updateSelfPaintingLayer();
 }
 
 } // namespace blink