Fix leaking of RenderFrames.

content/browser/frame_host/render_frame_host_impl.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/render_frame_host_impl.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "base/command_line.h"
@@ skipping 240 matching lines @@
   // RenderFrameHost during cleanup.
   ClearAllWebUI();
 
   GetProcess()->RemoveRoute(routing_id_);
   g_routing_id_frame_map.Get().erase(
       RenderFrameHostID(GetProcess()->GetID(), routing_id_));
 
   if (delegate_ && render_frame_created_)
     delegate_->RenderFrameDeleted(this);
 
-  // If this was swapped out, it already decremented the active frame count of
-  // the SiteInstance it belongs to.
-  if (IsRFHStateActive(rfh_state_))
+  if (IsRFHStateActive(rfh_state_)) {
+    // If this was swapped out, it already decremented the active frame count of
+    // the SiteInstance it belongs to.
     GetSiteInstance()->decrement_active_frame_count();
 
+    // In the case of swapping with a RenderFrameProxy, cleanup is already
+    // handled on the renderer process side. However, in all other cases the
+    // corresponding RenderFrame also needs to be cleaned up.
+    if (!frame_tree_node_->IsMainFrame() && render_frame_created_)

[Charlie Reis, 2015/12/11 20:10:14]

Hmm, this condition and the comment above seem to be talking about different
things.  It's not obvious how we're skipping the IPC in the "swapping with a
RenderFrameProxy" case-- maybe that makes IsRFHStateActive return false?

I think both of these blocks might be easier to read if we split them up. 
Something like:

bool is_active = IsRFHStateActive(rfh_state_);

// If this is swapping out, it already decremented the active frame count
// of the SiteInstance it belongs to.
if (is_active)
  GetSiteInstance()->decrement_active_frame_count();

// If this is swapping with a RenderFrameProxy, the RenderFrame will already
// be deleted in the renderer process. Main frame RenderFrames will be
// cleaned up as part of deleting their RenderView. In all other cases, the
// RenderFrame should be cleaned up (if it exists).
if (is_active && !frame_tree_node_->IsMainFrame() && render_frame_created_)
  Send(new FrameMsg_Detach(routing_id_));

[nasko, 2015/12/14 21:00:02]

Done.

+      Send(new FrameMsg_Detach(routing_id_));
+  }
+
   // NULL out the swapout timer; in crash dumps this member will be null only if
   // the dtor has run.
   swapout_event_monitor_timeout_.reset();
 
   for (const auto& iter: visual_state_callbacks_) {
     iter.second.Run(false);
   }
 
   if (render_widget_host_ &&
       render_widget_host_->owned_by_render_frame_host()) {
@@ skipping 2224 matching lines @@
   *dst = src;
 
   if (src.routing_id != -1)
     dst->tree_id = RoutingIDToAXTreeID(src.routing_id);
 
   if (src.parent_routing_id != -1)
     dst->parent_tree_id = RoutingIDToAXTreeID(src.parent_routing_id);
 }
 
 }  // namespace content