[Not for review] Add TRACE_EVENTs and chrome://flags for preconnect

chrome/browser/net/predictor.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 "chrome/browser/net/predictor.h"
 
 #include <algorithm>
 #include <cmath>
 #include <iterator>
 #include <set>
 #include <sstream>
 #include <utility>
 
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/compiler_specific.h"
 #include "base/containers/mru_cache.h"
 #include "base/feature_list.h"
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/single_thread_task_runner.h"
 #include "base/stl_util.h"
 #include "base/strings/stringprintf.h"
 #include "base/threading/thread_restrictions.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "base/time/time.h"
+#include "base/trace_event/trace_event.h"
 #include "base/values.h"
 #include "chrome/browser/io_thread.h"
 #include "chrome/browser/prefs/session_startup_pref.h"
 #include "chrome/browser/profiles/profile_io_data.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/pref_names.h"
 #include "components/pref_registry/pref_registry_syncable.h"
 #include "components/prefs/pref_service.h"
 #include "components/prefs/scoped_user_pref_update.h"
 #include "content/public/browser/browser_thread.h"
@@ skipping 713 matching lines @@
   // TODO(csharrison): The observer should only be notified after the null check
   // for the ProfileIOData. The predictor tests should be fixed to allow for
   // this, as they currently expect a callback with no getter.
   if (observer_) {
     observer_->OnPreconnectUrl(
         url, first_party_for_cookies, motivation, count);
   }
 
   if (!profile_io_data_)
     return;
-
+  TRACE_EVENT2("net", "Predictor::PreconnectUrlOnIOThread", "url",
+               original_url.spec(), "motivation", static_cast<int>(motivation));
   // Translate the motivation from UrlRequest motivations to HttpRequest
   // motivations.
   net::HttpRequestInfo::RequestMotivation request_motivation =
       net::HttpRequestInfo::NORMAL_MOTIVATION;
   switch (motivation) {
     case UrlInfo::OMNIBOX_MOTIVATED:
       request_motivation = net::HttpRequestInfo::OMNIBOX_MOTIVATED;
       break;
     case UrlInfo::LEARNED_REFERAL_MOTIVATED:
       request_motivation = net::HttpRequestInfo::PRECONNECT_MOTIVATED;
@@ skipping 58 matching lines @@
 
 enum SubresourceValue {
   PRECONNECTION,
   PRERESOLUTION,
   TOO_NEW,
   SUBRESOURCE_VALUE_MAX
 };
 
 void Predictor::PrepareFrameSubresources(const GURL& original_url,
                                          const GURL& first_party_for_cookies) {
+  TRACE_EVENT1("net", "Predictor::PrepareFrameSubresources", "url",
+               original_url.spec());
   // Apply HSTS redirect early so it is taken into account when looking up
   // subresources.
   GURL url = GetHSTSRedirectOnIOThread(original_url);
 
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   DCHECK_EQ(url.GetWithEmptyPath(), url);
   DCHECK(PredictorEnabled());
   // Peek here, and Get after logging the index into the MRU.
   Referrers::iterator it = referrers_.Get(url);
   if (referrers_.end() == it) {
@@ skipping 348 matching lines @@
 }
 
 void SimplePredictor::ShutdownOnUIThread() {
   SetShutdown(true);
 }
 
 bool SimplePredictor::CanPrefetchAndPrerender() const { return true; }
 bool SimplePredictor::CanPreresolveAndPreconnect() const { return true; }
 
 }  // namespace chrome_browser_net