Adding instrumentation to locate the source of jankiness.

net/tools/net_watcher/net_watcher.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.
 
 // This is a small utility that watches for and logs network changes.
 
 #include <string>
 
 #include "base/at_exit.h"
 #include "base/basictypes.h"
 #include "base/command_line.h"
 #include "base/compiler_specific.h"
 #include "base/json/json_writer.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop/message_loop.h"
+#include "base/profiler/scoped_tracker.h"
 #include "base/values.h"
 #include "build/build_config.h"
 #include "net/base/network_change_notifier.h"
 #include "net/proxy/proxy_config.h"
 #include "net/proxy/proxy_config_service.h"
 #include "net/proxy/proxy_service.h"
 
 #if defined(USE_GLIB) && !defined(OS_CHROMEOS)
 #include <glib-object.h>
 #endif
@@ skipping 80 matching lines @@
   void OnNetworkChanged(
       net::NetworkChangeNotifier::ConnectionType type) override {
     LOG(INFO) << "OnNetworkChanged("
               << ConnectionTypeToString(type) << ")";
   }
 
   // net::ProxyConfigService::Observer implementation.
   void OnProxyConfigChanged(
       const net::ProxyConfig& config,
       net::ProxyConfigService::ConfigAvailability availability) override {
+    // TODO(pkasting): Remove ScopedTracker below once crbug.com/455942 is
+    // fixed.
+    tracked_objects::ScopedTracker tracking_profile(
+        FROM_HERE_WITH_EXPLICIT_FUNCTION(
+            "455942 NetWatcher::OnProxyConfigChanged"));
     LOG(INFO) << "OnProxyConfigChanged("
               << ProxyConfigToString(config) << ", "
               << ConfigAvailabilityToString(availability) << ")";
   }
 
  private:
   DISALLOW_COPY_AND_ASSIGN(NetWatcher);
 };
 
 }  // namespace
@@ skipping 61 matching lines @@
   proxy_config_service->RemoveObserver(&net_watcher);
 
   // Uses |network_change_notifier|.
   net::NetworkChangeNotifier::RemoveDNSObserver(&net_watcher);
   net::NetworkChangeNotifier::RemoveConnectionTypeObserver(&net_watcher);
   net::NetworkChangeNotifier::RemoveIPAddressObserver(&net_watcher);
   net::NetworkChangeNotifier::RemoveNetworkChangeObserver(&net_watcher);
 
   return 0;
 }