Detach old frame on WebFrame::swap.

content/renderer/render_frame_proxy.cc

Index: content/renderer/render_frame_proxy.cc
diff --git a/content/renderer/render_frame_proxy.cc b/content/renderer/render_frame_proxy.cc
index 54d8085ac5b3d49dbb44e3df4f0646e361ba50d8..7d8207af0c6f37aa5e433e6125450363f3a6c5d5 100644
--- a/content/renderer/render_frame_proxy.cc
+++ b/content/renderer/render_frame_proxy.cc
@@ -310,7 +310,11 @@ void RenderFrameProxy::OnDidUpdateOrigin(const url::Origin& origin) {
 }
 
 void RenderFrameProxy::frameDetached() {
-  if (web_frame_->parent()) {
+  frameDetached(false);
+}
+
+void RenderFrameProxy::frameDetached(bool for_replacement) {
+  if (!for_replacement && web_frame_->parent()) {
     web_frame_->parent()->removeChild(web_frame_);
 
     // Let the browser process know this subframe is removed, so that it is