Null out a field in the RenderFrameHostImpl dtor.

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 "base/bind.h"
 #include "base/command_line.h"
 #include "base/containers/hash_tables.h"
 #include "base/lazy_instance.h"
@@ skipping 157 matching lines @@
   FrameAccessibility::GetInstance()->OnRenderFrameHostDestroyed(this);
 
   // If this was swapped out, it already decremented the active frame count of
   // the SiteInstance it belongs to.
   if (IsRFHStateActive(rfh_state_))
     GetSiteInstance()->decrement_active_frame_count();
 
   // Notify the FrameTree that this RFH is going away, allowing it to shut down
   // the corresponding RenderViewHost if it is no longer needed.
   frame_tree_->UnregisterRenderFrameHost(this);
+
+  // NULL out the swapout timer; in crash dumps this member will be null only if
+  // the dtor has run.
+  swapout_event_monitor_timeout_.reset();

[Evan Stade, 2014/12/10 22:02:18]

sorta surprised scoped_ptr doesn't already null out the pointer in its
destructor

[ncarter (slow), 2014/12/10 22:09:50]

I was surprised too, but it turns out that ~scoped_ptr_impl just invokes the
deleter (versus calling reset(), which would write nullptr to the ptr field).
Relevant lines:

https://code.google.com/p/chromium/codesearch#chromium/src/base/memory/scoped...

https://code.google.com/p/chromium/codesearch#chromium/src/base/memory/scoped...

 }
 
 int RenderFrameHostImpl::GetRoutingID() {
   return routing_id_;
 }
 
 SiteInstanceImpl* RenderFrameHostImpl::GetSiteInstance() {
   return render_view_host_->GetSiteInstance();
 }
 
@@ skipping 1388 matching lines @@
 void RenderFrameHostImpl::DidUseGeolocationPermission() {
   RenderFrameHost* top_frame = frame_tree_node()->frame_tree()->GetMainFrame();
   GetContentClient()->browser()->RegisterPermissionUsage(
       PERMISSION_GEOLOCATION,
       delegate_->GetAsWebContents(),
       GetLastCommittedURL().GetOrigin(),
       top_frame->GetLastCommittedURL().GetOrigin());
 }
 
 }  // namespace content