Always create FrameTreeNodes and RenderFrameHosts for every frame.

content/renderer/render_view_impl.cc

 // Copyright (c) 2012 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/renderer/render_view_impl.h"
 
 #include <algorithm>
 #include <cmath>
 
 #include "base/auto_reset.h"
@@ skipping 937 matching lines @@
       ShouldUseTransitionCompositing(device_scale_factor_));
   webview()->settings()->setAcceleratedCompositingForFixedRootBackgroundEnabled(
       ShouldUseAcceleratedFixedRootBackground(device_scale_factor_));
   webview()->settings()->setAcceleratedCompositingForScrollableFramesEnabled(
       ShouldUseAcceleratedCompositingForScrollableFrames(device_scale_factor_));
   webview()->settings()->setCompositedScrollingForFramesEnabled(
       ShouldUseCompositedScrollingForFrames(device_scale_factor_));
 
   ApplyWebPreferences(webkit_preferences_, webview());
 
-  main_render_frame_.reset(
-      RenderFrameImpl::Create(this, params->main_frame_routing_id));
+  main_render_frame_ =
+      RenderFrameImpl::Create(this, params->main_frame_routing_id);
   // The main frame WebFrame object is closed by
   // RenderViewImpl::frameDetached().
-  webview()->setMainFrame(WebFrame::create(main_render_frame_.get()));
+  webview()->setMainFrame(WebFrame::create(main_render_frame_));
 
   if (switches::IsTouchDragDropEnabled())
     webview()->settings()->setTouchDragDropEnabled(true);
 
   if (switches::IsTouchEditingEnabled())
     webview()->settings()->setTouchEditingEnabled(true);
 
   if (!params->frame_name.empty())
     webview()->mainFrame()->setName(params->frame_name);
 
@@ skipping 1575 matching lines @@
   int id = enumeration_completion_id_++;
   enumeration_completions_[id] = chooser_completion;
   return Send(new ViewHostMsg_EnumerateDirectory(
       routing_id_,
       id,
       base::FilePath::FromUTF16Unsafe(path)));
 }
 
 void RenderViewImpl::initializeHelperPluginWebFrame(
     blink::WebHelperPlugin* plugin) {
-  plugin->initializeFrame(main_render_frame_.get());
+  plugin->initializeFrame(main_render_frame_);
 }
 
 void RenderViewImpl::didStartLoading() {
   if (is_loading_) {
     DVLOG(1) << "didStartLoading called while loading";
     return;
   }
 
   is_loading_ = true;
 
@@ skipping 591 matching lines @@
   // opener after hearing about it from the browser, and the browser does not
   // (yet) care about subframe openers.
   if (is_swapped_out_ || frame->parent())
     return;
 
   // Notify WebContents and all its swapped out RenderViews.
   Send(new ViewHostMsg_DidDisownOpener(routing_id_));
 }
 
 void RenderViewImpl::frameDetached(WebFrame* frame) {
+  if (!frame->parent()) {
+    // We cannot rely on our main_render_frame_ anymore.  It will be deleted as
+    // part of RenderFrameImpl::frameDetached.  We expect to be deleted
+    // right away, but we clear this out to be safe.
+    main_render_frame_ = NULL;

[Charlie Reis, 2013/11/21 23:59:15]

I added this as well, since I didn't like the idea of leaving main_render_frame_
as garbage when it gets detached.

(It doesn't appear that RenderViewImpl gets deleted in the same task on the
message loop, but perhaps there's some guarantee it will be the next task? 
Otherwise we'd have lots of problems when accessing webview(), etc. after this
point.)

+  }
   FOR_EACH_OBSERVER(RenderViewObserver, observers_, FrameDetached(frame));
 }
 
 void RenderViewImpl::willClose(WebFrame* frame) {
   FOR_EACH_OBSERVER(RenderViewObserver, observers_, FrameWillClose(frame));
 }
 
 void RenderViewImpl::didMatchCSS(
     WebFrame* frame,
     const WebVector<WebString>& newly_matching_selectors,
@@ skipping 3499 matching lines @@
   for (size_t i = 0; i < icon_urls.size(); i++) {
     WebURL url = icon_urls[i].iconURL();
     if (!url.isEmpty())
       urls.push_back(FaviconURL(url,
                                 ToFaviconType(icon_urls[i].iconType())));
   }
   SendUpdateFaviconURL(urls);
 }
 
 }  // namespace content