PlzNavigate: improve tracking of improper subframe swap-out.

content/browser/frame_host/frame_tree_node.cc

 // Copyright 2013 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 "content/browser/frame_host/frame_tree_node.h"
 
 #include <queue>
 
 #include "base/command_line.h"
 #include "base/stl_util.h"
@@ skipping 53 matching lines @@
   std::pair<FrameTreeNodeIDMap::iterator, bool> result =
       g_frame_tree_node_id_map.Get().insert(
           std::make_pair(frame_tree_node_id_, this));
   CHECK(result.second);
 }
 
 FrameTreeNode::~FrameTreeNode() {
   frame_tree_->FrameRemoved(this);
 
   g_frame_tree_node_id_map.Get().erase(frame_tree_node_id_);
-  if (base::CommandLine::ForCurrentProcess()->HasSwitch(
-          switches::kEnableBrowserSideNavigation)) {
-    navigator_->CancelNavigation(this);
-  }

[carlosk, 2015/04/08 09:01:48]

N::CancelNavigation -> RFHM::CleanUpNavigation -> RFHM::DiscardUnusedFrame,
which would swap out the RFH if there should be more references to its
SiteInstance.

So in RenderFrameHostManagerTest::DetachPendingChild, when it sends the first
FrameHostMsg_Detach an extra reference to the SiteInstance was kept by the
swapped out RFH when it shouldn't. This caused the last check in this test to
fail (site_instance->HasOneRef()).

[clamy, 2015/04/08 11:29:11]

I think this needs to remain in place otherwise the navigation request for the
subframes does not get cleaned up. We ran into very similar issues when I was
fixing this test in the first place, and Nasko mentioned that creating the
swapped out RFH in the parent there might not make much sense. I suggest you
talk to him to see how to address the problem, because I don't think this is the
best approach.

[carlosk, 2015/04/08 16:05:39]

Acknowledged.

 }
 
 bool FrameTreeNode::IsMainFrame() const {
   return frame_tree_->root() == this;
 }
 
 void FrameTreeNode::AddChild(scoped_ptr<FrameTreeNode> child,
                              int process_id,
                              int frame_routing_id) {
   // Child frame must always be created in the same process as the parent.
@@ skipping 80 matching lines @@
 }
 
 bool FrameTreeNode::CommitPendingSandboxFlags() {
   bool did_change_flags =
       effective_sandbox_flags_ != replication_state_.sandbox_flags;
   effective_sandbox_flags_ = replication_state_.sandbox_flags;
   return did_change_flags;
 }
 
 }  // namespace content