Use ChildFrameDisconnector when detaching child frames of a LocalFrame.

third_party/WebKit/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 "core/frame/RemoteFrame.h"
 
 #include "bindings/core/v8/WindowProxy.h"
 #include "bindings/core/v8/WindowProxyManager.h"
 #include "core/dom/RemoteSecurityContext.h"
 #include "core/frame/LocalFrame.h"
@@ skipping 178 matching lines @@
 
     ASSERT(owner());
     toHTMLFrameOwnerElement(owner())->setNeedsCompositingUpdate();
 }
 
 void RemoteFrame::advanceFocus(WebFocusType type, LocalFrame* source)
 {
     client()->advanceFocus(type, source);
 }
 
+void RemoteFrame::detachChildren()
+{
+    using FrameVector = HeapVector<Member<Frame>>;
+    FrameVector childrenToDetach;
+    childrenToDetach.reserveCapacity(tree().childCount());
+    for (Frame* child = tree().firstChild(); child; child = child->tree().nextSibling())

[esprehn, 2016/07/11 19:39:30]

why do we need to keep this code path for remote frames? I think in most pages
the frame tree is interleaved Remote and Local frames so you're likely to end up
down this code path really often.

[dcheng, 2016/07/12 01:14:41]

ChildFrameDisconnector is based on DOM nodes, which remote frames don't have, so
we need an alternate path for remote frames. It's a bit unfortunate, but it's
not much different from before: previously, both versions delegate to a
non-virtual Frame::detachChildren: now they just happen to delegate to different
implementations of detachChildren.

+        childrenToDetach.append(child);
+    for (const auto& child : childrenToDetach)
+        child->detach(FrameDetachType::Remove);

[esprehn, 2016/07/13 02:35:45]

this doesn't use a SubframeLoadingDisabler, so the script in here can load more
frames which then get missed by the above logic in the RemoteFrame case. That's
probably a security bug that already exists.

+}
+
 } // namespace blink