Trace FrameTreeNode Snapshots

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 904 matching lines @@
   // DidCommitProvisionalLoad IPC without a prior DidStartProvisionalLoad
   // message.
   if (!navigation_handle_) {
     navigation_handle_ = NavigationHandleImpl::Create(
         validated_params.url, frame_tree_node_);
   }
 
   accessibility_reset_count_ = 0;
   frame_tree_node()->navigator()->DidNavigate(this, validated_params);
 
+  frame_tree_->TraceSnapshot();

[clamy, 2015/10/13 11:48:17]

I would rather have this execute inside NavigatorImpl::DidNavigate. This way we
can have it not executed if the renderer did not actually navigate (eg in
page-navigations).

[benjhayden, 2015/10/22 17:24:21]

I put it after the !did_navigate early return, but there's a comment saying not
to put anything else there, so I'm not sure if I did it right.

[nasko, 2015/10/23 15:52:04]

Now that I think about this. Why do we need to hook this into the FrameTree
itself? Why can't the tracer just be a WebContentsObserver, which tracks
RenderFrameCreated/RenderFrameDeleted/DidFinishNavigation?

If we go that route, it will be possible to even dump trees of nested
WebContents, which is going to be even more awesome for cases of Chrome apps
using <webview>, once we move it to out-of-process iframes.

+
   // For a top-level frame, there are potential security concerns associated
   // with displaying graphics from a previously loaded page after the URL in
   // the omnibar has been changed. It is unappealing to clear the page
   // immediately, but if the renderer is taking a long time to issue any
   // compositor output (possibly because of script deliberately creating this
   // situation) then we clear it after a while anyway.
   // See https://crbug.com/497588.
   if (frame_tree_node_->IsMainFrame() && GetView() &&
       !validated_params.was_within_same_page) {
     RenderWidgetHostImpl::From(GetView()->GetRenderWidgetHost())
@@ skipping 1332 matching lines @@
             BrowserPluginInstanceIDToAXTreeID(value)));
         break;
       case AX_CONTENT_INT_ATTRIBUTE_LAST:
         NOTREACHED();
         break;
     }
   }
 }
 
 }  // namespace content