Trace FrameTreeNode Snapshots

content/browser/frame_host/navigator_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/navigator_impl.h"
 
 #include "base/command_line.h"
 #include "base/metrics/histogram.h"
 #include "base/time/time.h"
 #include "content/browser/frame_host/frame_tree.h"
@@ skipping 476 matching lines @@
                                         params.url,
                                         transition_type);
     render_frame_host->navigation_handle()->DidCommitNavigation(
         is_navigation_within_page, render_frame_host);
     render_frame_host->SetNavigationHandle(nullptr);
   }
 
   if (!did_navigate)
     return;  // No navigation happened.
 
+  render_frame_host->frame_tree_node()->frame_tree()->TraceSnapshot();

[clamy, 2015/10/26 14:45:13]

I think this should move to RenderFrameHostManager::CommitPendingIfNecessary
when we commit or destroy the pending/speculative RFH. It would also be
interesting to trace the FrameTree when we create/destroy either of those RFH in
RFHM::GetFrameHostForNavigation and RFHM::UpdateStateForNavigate.

Another option would be to trace the FrameTree when a RFH is created/destroyed
(but we generally try to avoid doing a lot of work in the
constructor/destructor).

[nasko, 2015/10/26 15:59:23]

I would rather not trace in RFHM's method that allocate RFHs that aren't
committed yet. This exposes a level of detail that only few devs in Chrome
understand and is rarely something people care about.
 
This will allow the concept of pending/speculative RFH to leak out, wouldn't it?
I'm against leaking this information.

+
   // DO NOT ADD MORE STUFF TO THIS FUNCTION! Your component should either listen
   // for the appropriate notification (best) or you can add it to
   // DidNavigateMainFramePostCommit / DidNavigateAnyFramePostCommit (only if
   // necessary, please).
 
   // TODO(carlosk): Move this out when PlzNavigate implementation properly calls
   // the observer methods.
   RecordNavigationMetrics(details, params, site_instance);
 
   // Run post-commit tasks.
@@ skipping 439 matching lines @@
       entry->set_should_replace_entry(pending_entry->should_replace_entry());
       entry->SetRedirectChain(pending_entry->GetRedirectChain());
     }
     controller_->SetPendingEntry(entry.Pass());
     if (delegate_)
       delegate_->NotifyChangedNavigationState(content::INVALIDATE_TYPE_URL);
   }
 }
 
 }  // namespace content