PlzNavigate: add initial traces for new TBM benchmarks.

content/browser/loader/navigation_url_loader_impl.cc

 // Copyright 2014 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/loader/navigation_url_loader_impl.h"
 
 #include "base/bind.h"
 #include "base/location.h"
+#include "base/trace_event/trace_event.h"
 #include "content/browser/frame_host/navigation_request_info.h"
 #include "content/browser/loader/navigation_url_loader_delegate.h"
 #include "content/browser/loader/navigation_url_loader_impl_core.h"
 #include "content/browser/service_worker/service_worker_navigation_handle.h"
 #include "content/public/browser/browser_context.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/stream_handle.h"
 
 namespace content {
 
 NavigationURLLoaderImpl::NavigationURLLoaderImpl(
     BrowserContext* browser_context,
     scoped_ptr<NavigationRequestInfo> request_info,
     ServiceWorkerNavigationHandle* service_worker_handle,
     NavigationURLLoaderDelegate* delegate)
     : delegate_(delegate), weak_factory_(this) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 
   core_ = new NavigationURLLoaderImplCore(weak_factory_.GetWeakPtr());
+  TRACE_EVENT_ASYNC_BEGIN_WITH_TIMESTAMP1(

[clamy, 2015/12/18 15:42:11]

This is called on the UI thread while the end happens on the IO thread. Is that
an issue?

[carlosk, 2015/12/18 17:23:21]

Nope, it's supported behavior:
https://code.google.com/p/chromium/codesearch#chromium/src/base/trace_event/c...

+      "navigation", "Navigation timeToResponseStarted", core_,
+      request_info->common_params.navigation_start.ToInternalValue(),
+      "FrameTreeNode id", request_info->frame_tree_node_id);
   ServiceWorkerNavigationHandleCore* service_worker_handle_core =
       service_worker_handle ? service_worker_handle->core() : nullptr;
   BrowserThread::PostTask(
       BrowserThread::IO, FROM_HERE,
       base::Bind(&NavigationURLLoaderImplCore::Start, base::Unretained(core_),
                  browser_context->GetResourceContext(),
                  service_worker_handle_core, base::Passed(&request_info)));
 }
 
 NavigationURLLoaderImpl::~NavigationURLLoaderImpl() {
@@ skipping 35 matching lines @@
   delegate_->OnRequestFailed(in_cache, net_error);
 }
 
 void NavigationURLLoaderImpl::NotifyRequestStarted(base::TimeTicks timestamp) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 
   delegate_->OnRequestStarted(timestamp);
 }
 
 }  // namespace content