Detach old frame on WebFrame::swap.

content/renderer/render_frame_impl.cc

Index: content/renderer/render_frame_impl.cc
diff --git a/content/renderer/render_frame_impl.cc b/content/renderer/render_frame_impl.cc
index 7ae7fa1fd4ea88a1b1a64852127df30e142e7aa7..035017e7605c5b889024fc1492a55c1ce95f4e02 100644
--- a/content/renderer/render_frame_impl.cc
+++ b/content/renderer/render_frame_impl.cc
@@ -692,7 +692,8 @@ RenderFrameImpl::~RenderFrameImpl() {
     if (render_frame_proxy_) {
       // The following method calls back into this object and clears
       // |render_frame_proxy_|.
-      render_frame_proxy_->frameDetached();
+      render_frame_proxy_->frameDetached(
+          blink::WebRemoteFrameClient::DetachType::Remove);
     }
 
     // Ensure the RenderView doesn't point to this object, once it is destroyed.
@@ -2120,6 +2121,10 @@ void RenderFrameImpl::didDisownOpener(blink::WebLocalFrame* frame) {
 }
 
 void RenderFrameImpl::frameDetached(blink::WebFrame* frame) {
+  frameDetached(frame, DetachType::Remove);
+}
+
+void RenderFrameImpl::frameDetached(blink::WebFrame* frame, DetachType type) {
   // NOTE: This function is called on the frame that is being detached and not
   // the parent frame.  This is different from createChildFrame() which is
   // called on the parent frame.
@@ -2130,7 +2135,8 @@ void RenderFrameImpl::frameDetached(blink::WebFrame* frame) {
   FOR_EACH_OBSERVER(RenderViewObserver, render_view_->observers(),
                     FrameDetached(frame));
 
-  Send(new FrameHostMsg_Detach(routing_id_));
+  if (type == DetachType::Remove)

[Charlie Reis, 2015/06/01 23:41:46]

What other values can it be, and why would this method make sense with them?

I think some comments here would help a lot.  It looks like Swap is the other
value, so maybe it makes sense to mention why we don't send this IPC or call
removeChild when we're doing a swap.

[lfg, 2015/06/02 16:00:01]

I've added some comments, please take a look.

[Charlie Reis, 2015/06/02 17:05:27]

Much better, thanks.

+    Send(new FrameHostMsg_Detach(routing_id_));
 
   // The |is_detaching_| flag disables Send(). FrameHostMsg_Detach must be
   // sent before setting |is_detaching_| to true.
@@ -2150,7 +2156,9 @@ void RenderFrameImpl::frameDetached(blink::WebFrame* frame) {
             switches::kSitePerProcess) && render_widget_) {
       render_widget_->UnregisterRenderFrame(this);
     }
-    frame->parent()->removeChild(frame);
+
+    if (type == DetachType::Remove)
+      frame->parent()->removeChild(frame);
   }
 
   // |frame| is invalid after here.  Be sure to clear frame_ as well, since this