Adding instrumentation to locate the source of jankiness.

chrome/browser/extensions/updater/extension_downloader.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/extensions/updater/extension_downloader.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/files/file_path.h"
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/metrics/histogram.h"
 #include "base/metrics/sparse_histogram.h"
+#include "base/profiler/scoped_profile.h"
 #include "base/stl_util.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
 #include "base/time/time.h"
 #include "base/version.h"
 #include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/extensions/updater/extension_cache.h"
 #include "chrome/browser/extensions/updater/request_queue_impl.h"
 #include "chrome/common/chrome_switches.h"
@@ skipping 453 matching lines @@
   // Update checks can be interrupted if a network change is detected; this is
   // common for the retail mode AppPack on ChromeOS. Retrying once should be
   // enough to recover in those cases; let the fetcher retry up to 3 times
   // just in case. http://crosbug.com/130602
   manifest_fetcher_->SetAutomaticallyRetryOnNetworkChanges(3);
   manifest_fetcher_->Start();
 }
 
 void ExtensionDownloader::OnURLFetchComplete(
     const net::URLFetcher* source) {
+  // TODO(vadimt): Remove ScopedProfile below once crbug.com/422577 is fixed.
+  tracked_objects::ScopedProfile tracking_profile(
+      FROM_HERE_WITH_EXPLICIT_FUNCTION(
+          "422577 ExtensionDownloader::OnURLFetchComplete"));
+
   VLOG(2) << source->GetResponseCode() << " " << source->GetURL();
 
   if (source == manifest_fetcher_.get()) {
     std::string data;
     source->GetResponseAsString(&data);
     OnManifestFetchComplete(source->GetURL(),
                             source->GetStatus(),
                             source->GetResponseCode(),
                             source->GetBackoffDelay(),
                             data);
@@ skipping 456 matching lines @@
       ping_mode = ManifestFetchData::PING_WITH_METRICS;
     } else {
       ping_mode = ManifestFetchData::PING;
     }
   }
   return new ManifestFetchData(
       update_url, request_id, brand_code_, manifest_query_params_, ping_mode);
 }
 
 }  // namespace extensions