PlzNavigate: add initial traces for new TBM benchmarks.

content/browser/web_contents/web_contents_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/browser/web_contents/web_contents_impl.h"
 
 #include <utility>
 
 #include "base/command_line.h"
 #include "base/lazy_instance.h"
@@ skipping 3560 matching lines @@
   is_loading_ = is_loading;
   waiting_for_response_ = is_loading;
   is_load_to_different_document_ = to_different_document;
 
   if (delegate_)
     delegate_->LoadingStateChanged(this, to_different_document);
   NotifyNavigationStateChanged(INVALIDATE_TYPE_LOAD);
 
   std::string url = (details ? details->url.possibly_invalid_spec() : "NULL");
   if (is_loading) {
-    TRACE_EVENT_ASYNC_BEGIN1("browser,navigation", "WebContentsImpl Loading",
-                             this, "URL", url);
+    TRACE_EVENT_ASYNC_BEGIN2("browser,navigation", "WebContentsImpl Loading",
+                             this, "URL", url, "Main FrameTreeNode id",
+                             GetFrameTree()->root()->frame_tree_node_id());
     FOR_EACH_OBSERVER(WebContentsObserver, observers_, DidStartLoading());
   } else {
     TRACE_EVENT_ASYNC_END1("browser,navigation", "WebContentsImpl Loading",
                            this, "URL", url);
     FOR_EACH_OBSERVER(WebContentsObserver, observers_, DidStopLoading());
   }
 
   // TODO(avi): Remove. http://crbug.com/170921
   int type = is_loading ? NOTIFICATION_LOAD_START : NOTIFICATION_LOAD_STOP;
   NotificationDetails det = NotificationService::NoDetails();
@@ skipping 1122 matching lines @@
     const WebContentsObserver::MediaPlayerId& id) {
   FOR_EACH_OBSERVER(WebContentsObserver, observers_, MediaStartedPlaying(id));
 }
 
 void WebContentsImpl::MediaStoppedPlaying(
     const WebContentsObserver::MediaPlayerId& id) {
   FOR_EACH_OBSERVER(WebContentsObserver, observers_, MediaStoppedPlaying(id));
 }
 
 }  // namespace content