Add/improve tracing in navigation.

content/browser/loader/cross_site_resource_handler.cc

Index: content/browser/loader/cross_site_resource_handler.cc
diff --git a/content/browser/loader/cross_site_resource_handler.cc b/content/browser/loader/cross_site_resource_handler.cc
index a812fd92b4d30c5cb29704c8e7dfd0faaf8ada19..376044cc7f48c98485cefaee27bd3c70b8e33b6d 100644
--- a/content/browser/loader/cross_site_resource_handler.cc
+++ b/content/browser/loader/cross_site_resource_handler.cc
@@ -293,6 +293,8 @@ void CrossSiteResourceHandler::OnResponseCompleted(
 // We can now send the response to the new renderer, which will cause
 // WebContentsImpl to swap in the new renderer and destroy the old one.
 void CrossSiteResourceHandler::ResumeResponse() {
+  TRACE_EVENT_ASYNC_END0(
+      "navigation", "CrossSiteResourceHandler::StartCrossSiteTransition", this);

[Charlie Reis, 2014/08/27 22:05:13]

What's the usual naming scheme for events with begin and end?  Is it usually the
method name that started it, or more of a semantic name like
"CrossSiteResourceHandler transition"?  I ask because it's currently ambiguous
in the trace diagram whether this is a really long-running method or an event
with separate begin and end events.

[nasko, 2014/08/27 23:30:01]

The title of the event (second param) is free form. I kept it to method names,
but we can change it to anything we want if it makes more sense.

   DCHECK(request());
   in_cross_site_transition_ = false;
   ResourceRequestInfoImpl* info = GetRequestInfo();
@@ -334,6 +336,8 @@ void CrossSiteResourceHandler::SetLeakRequestsForTesting(
 // Prepare to transfer the response to a new RenderFrameHost.
 void CrossSiteResourceHandler::StartCrossSiteTransition(
     ResourceResponse* response) {
+  TRACE_EVENT_ASYNC_BEGIN0(
+      "navigation", "CrossSiteResourceHandler::StartCrossSiteTransition", this);
   in_cross_site_transition_ = true;
   response_ = response;