Trace FrameTreeNode Snapshots

content/browser/frame_host/frame_tree_node.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/frame_tree_node.h"
 
 #include <queue>
 #include <utility>
 
 #include "base/macros.h"
 #include "base/profiler/scoped_tracker.h"
 #include "base/stl_util.h"
 #include "content/browser/frame_host/frame_tree.h"
 #include "content/browser/frame_host/navigation_request.h"
 #include "content/browser/frame_host/navigator.h"
 #include "content/browser/frame_host/render_frame_host_impl.h"
+#include "content/browser/frame_host/traced_frame_tree_node.h"
 #include "content/browser/renderer_host/render_view_host_impl.h"
 #include "content/common/frame_messages.h"
 #include "content/common/site_isolation_policy.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/common/browser_side_navigation_policy.h"
 #include "third_party/WebKit/public/web/WebSandboxFlags.h"
 
 namespace content {
 
 namespace {
@@ skipping 71 matching lines @@
           unique_name,
           blink::WebSandboxFlags::None,
           false /* should enforce strict mixed content checking */),
       pending_sandbox_flags_(blink::WebSandboxFlags::None),
       frame_owner_properties_(frame_owner_properties),
       loading_progress_(kLoadingProgressNotStarted) {
   std::pair<FrameTreeNodeIdMap::iterator, bool> result =
       g_frame_tree_node_id_map.Get().insert(
           std::make_pair(frame_tree_node_id_, this));
   CHECK(result.second);
+
+  TRACE_EVENT_OBJECT_CREATED_WITH_ID(
+      "navigation", "FrameTreeNode",
+      TRACE_ID_WITH_SCOPE("FrameTreeNode", frame_tree_node_id_));
+  TraceSnapshot();

[nasko, 2016/03/03 21:41:32]

Is this call to TraceSnapshot() really needed? As you discovered, at this point
in time RFHM is not initialized, so you won't have any RFH information. There
will be a navigation that commits in this FTN, so maybe tracing a snapshot here
isn't needed.

[benjhayden, 2016/03/03 23:14:05]

Maybe, maybe not.
I put this TraceSnapshot() here because of a quirk in how idRefs are patched up
in catapult.
If a trace event E (such as another object snapshot (such as a child
FrameTreeNode)) contains an idRef to a FrameTreeNode N, and E's timestamp is
before the first snapshot of N, then E's idRef to N will not be able to be
patched up. It'll be a broken idRef.
So, it seems safer to always snapshot an object as soon as it's created.

If you like, I could replace this TraceSnapshot() call with a direct call to
TRACE_EVENT_OBJECT_SNAPSHOT_WITH_ID() *without* a TracedFrameTreeNode, so
there'll be a snapshot for idRefs, but TracedFrameTreeNode will be able to
assume that its FrameTreeNode will always be initialized.

+  base::trace_event::TraceLog::GetInstance()->AddEnabledStateObserver(this);
 }
 
 FrameTreeNode::~FrameTreeNode() {
   children_.clear();
   frame_tree_->FrameRemoved(this);
   FOR_EACH_OBSERVER(Observer, observers_, OnFrameTreeNodeDestroyed(this));
 
   if (opener_)
     opener_->RemoveObserver(opener_observer_.get());
 
   g_frame_tree_node_id_map.Get().erase(frame_tree_node_id_);
+
+  TRACE_EVENT_OBJECT_DELETED_WITH_ID(
+      "navigation", "FrameTreeNode",
+      TRACE_ID_WITH_SCOPE("FrameTreeNode", frame_tree_node_id_));
+  base::trace_event::TraceLog::GetInstance()->RemoveEnabledStateObserver(this);
 }
 
 void FrameTreeNode::AddObserver(Observer* observer) {
   observers_.AddObserver(observer);
 }
 
 void FrameTreeNode::RemoveObserver(Observer* observer) {
   observers_.RemoveObserver(observer);
 }
 
@@ skipping 36 matching lines @@
       scoped_ptr<FrameTreeNode> node_to_delete(std::move(*iter));
       children_.erase(iter);
       node_to_delete.reset();
       return;
     }
   }
 }
 
 void FrameTreeNode::ResetForNewProcess() {
   current_frame_host()->set_last_committed_url(GURL());
+  TraceSnapshot();
 
   // Remove child nodes from the tree, then delete them. This destruction
   // operation will notify observers.
   std::vector<scoped_ptr<FrameTreeNode>>().swap(children_);
 }
 
 void FrameTreeNode::SetOpener(FrameTreeNode* opener) {
   if (opener_) {
     opener_->RemoveObserver(opener_observer_.get());
     opener_observer_.reset();
   }
 
   opener_ = opener;
 
   if (opener_) {
     if (!opener_observer_)
       opener_observer_ = make_scoped_ptr(new OpenerDestroyedObserver(this));
     opener_->AddObserver(opener_observer_.get());
   }
 }
 
 void FrameTreeNode::SetCurrentURL(const GURL& url) {
   if (!has_committed_real_load_ && url != GURL(url::kAboutBlankURL))
     has_committed_real_load_ = true;
   current_frame_host()->set_last_committed_url(url);
+  TraceSnapshot();
 }
 
 void FrameTreeNode::SetCurrentOrigin(const url::Origin& origin) {
   if (!origin.IsSameOriginWith(replication_state_.origin))
     render_manager_.OnDidUpdateOrigin(origin);
   replication_state_.origin = origin;
 }
 
 void FrameTreeNode::SetFrameName(const std::string& name,
                                  const std::string& unique_name) {
@@ skipping 231 matching lines @@
     if (speculative_frame_host)
       speculative_frame_host->ResetLoadingState();
   } else {
     RenderFrameHostImpl* pending_frame_host =
         render_manager_.pending_frame_host();
     if (pending_frame_host)
       pending_frame_host->ResetLoadingState();
   }
 }
 
+void FrameTreeNode::OnTraceLogEnabled() {
+  TraceSnapshot();
+}
+
+void FrameTreeNode::TraceSnapshot() const {
+  TRACE_EVENT_OBJECT_SNAPSHOT_WITH_ID(
+      "navigation", "FrameTreeNode",
+      TRACE_ID_WITH_SCOPE("FrameTreeNode", frame_tree_node_id_),
+      scoped_ptr<base::trace_event::ConvertableToTraceFormat>(
+          new TracedFrameTreeNode(*this)));
+}
+
 }  // namespace content