Detach old frame on WebFrame::swap.

components/html_viewer/html_document.cc

Index: components/html_viewer/html_document.cc
diff --git a/components/html_viewer/html_document.cc b/components/html_viewer/html_document.cc
index 4f678954e1683bd86c7e6c070b814e99e598b4de..786f6885a643341dc2399e2fe47c8c3c87e570f9 100644
--- a/components/html_viewer/html_document.cc
+++ b/components/html_viewer/html_document.cc
@@ -255,6 +255,11 @@ blink::WebFrame* HTMLDocument::createChildFrame(
 }
 
 void HTMLDocument::frameDetached(blink::WebFrame* frame) {
+  frameDetached(frame, DetachType::Remove);
+}
+
+void HTMLDocument::frameDetached(blink::WebFrame* frame, DetachType type) {
+  DCHECK(type == DetachType::Remove);

[sky, 2015/06/02 23:01:40]

nit: DCHECK_EQ

   if (frame->parent())
     frame->parent()->removeChild(frame);