Don't crash while detaching a pending child frame under --site-per-process.

content/browser/frame_host/render_frame_host_manager.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_manager.h"
 
 #include <utility>
 
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
@@ skipping 49 matching lines @@
       render_frame_delegate_(render_frame_delegate),
       render_view_delegate_(render_view_delegate),
       render_widget_delegate_(render_widget_delegate),
       interstitial_page_(NULL),
       weak_factory_(this) {
   DCHECK(frame_tree_node_);
 }
 
 RenderFrameHostManager::~RenderFrameHostManager() {
   if (pending_render_frame_host_)
-    CancelPending();
+    UnsetPendingRenderFrameHost();
 
   // We should always have a current RenderFrameHost except in some tests.
   SetRenderFrameHost(scoped_ptr<RenderFrameHostImpl>());
 
   // Delete any swapped out RenderFrameHosts.
   STLDeleteValues(&proxy_hosts_);
 }
 
 void RenderFrameHostManager::Init(BrowserContext* browser_context,
                                   SiteInstance* site_instance,
@@ skipping 1503 matching lines @@
         new ViewMsg_EnableViewSourceMode(
             render_frame_host_->render_view_host()->GetRoutingID()));
   }
 
   return render_frame_host_.get();
 }
 
 void RenderFrameHostManager::CancelPending() {
   TRACE_EVENT1("navigation", "RenderFrameHostManager::CancelPending",
                "FrameTreeNode id", frame_tree_node_->frame_tree_node_id());
+  DiscardUnusedFrame(UnsetPendingRenderFrameHost());
+}
+
+scoped_ptr<RenderFrameHostImpl>
+RenderFrameHostManager::UnsetPendingRenderFrameHost() {
   scoped_ptr<RenderFrameHostImpl> pending_render_frame_host =
       pending_render_frame_host_.Pass();
 
   RenderViewDevToolsAgentHost::OnCancelPendingNavigation(
       pending_render_frame_host->render_view_host(),
       render_frame_host_->render_view_host());
 
   // We no longer need to prevent the process from exiting.
   pending_render_frame_host->GetProcess()->RemovePendingView();
 
-  DiscardUnusedFrame(pending_render_frame_host.Pass());
-
   pending_web_ui_.reset();
   pending_and_current_web_ui_.reset();
+
+  return pending_render_frame_host.Pass();
 }
 
 scoped_ptr<RenderFrameHostImpl> RenderFrameHostManager::SetRenderFrameHost(
     scoped_ptr<RenderFrameHostImpl> render_frame_host) {
   // Swap the two.
   scoped_ptr<RenderFrameHostImpl> old_render_frame_host =
       render_frame_host_.Pass();
   render_frame_host_ = render_frame_host.Pass();
 
   if (frame_tree_node_->IsMainFrame()) {
@@ skipping 61 matching lines @@
 void RenderFrameHostManager::DeleteRenderFrameProxyHost(
     SiteInstance* instance) {
   RenderFrameProxyHostMap::iterator iter = proxy_hosts_.find(instance->GetId());
   if (iter != proxy_hosts_.end()) {
     delete iter->second;
     proxy_hosts_.erase(iter);
   }
 }
 
 }  // namespace content