Adding instrumentation to locate the source of jankiness.

chrome/browser/net/pref_proxy_config_tracker_impl.cc

 // Copyright (c) 2011 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/pref_proxy_config_tracker_impl.h"
 
 #include "base/bind.h"
 #include "base/prefs/pref_registry_simple.h"
 #include "base/prefs/pref_service.h"
+#include "base/profiler/scoped_tracker.h"
 #include "base/values.h"
 #include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/prefs/proxy_config_dictionary.h"
 #include "chrome/common/pref_names.h"
 #include "components/pref_registry/pref_registry_syncable.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/notification_details.h"
 #include "content/public/browser/notification_source.h"
 
 using content::BrowserThread;
@@ skipping 74 matching lines @@
   ConfigAvailability availability = GetLatestProxyConfig(&new_config);
   if (availability != CONFIG_PENDING) {
     FOR_EACH_OBSERVER(net::ProxyConfigService::Observer, observers_,
                       OnProxyConfigChanged(new_config, availability));
   }
 }
 
 void ChromeProxyConfigService::OnProxyConfigChanged(
     const net::ProxyConfig& config,
     ConfigAvailability availability) {
+  // TODO(pkasting): Remove ScopedTracker below once crbug.com/455942 is fixed.
+  tracked_objects::ScopedTracker tracking_profile(
+      FROM_HERE_WITH_EXPLICIT_FUNCTION(
+          "455942 ChromeProxyConfigService::OnProxyConfigChanged"));
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
 
   // Check whether there is a proxy configuration defined by preferences. In
   // this case that proxy configuration takes precedence and the change event
   // from the delegate proxy service can be disregarded.
   if (!PrefProxyConfigTrackerImpl::PrefPrecedes(pref_config_state_)) {
     net::ProxyConfig actual_config;
     availability = GetLatestProxyConfig(&actual_config);
     FOR_EACH_OBSERVER(net::ProxyConfigService::Observer, observers_,
                       OnProxyConfigChanged(actual_config, availability));
@@ skipping 234 matching lines @@
       (config_state_ != ProxyPrefs::CONFIG_UNSET &&
        !pref_config_.Equals(new_config))) {
     config_state_ = config_state;
     if (config_state_ != ProxyPrefs::CONFIG_UNSET)
       pref_config_ = new_config;
     update_pending_ = true;
   }
   if (update_pending_)
     OnProxyConfigChanged(config_state, new_config);
 }