Adding instrumentation to locate the source of jankiness.

net/url_request/url_request_simple_job.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 "net/url_request/url_request_simple_job.h"
 
 #include <vector>
 
 #include "base/bind.h"
 #include "base/compiler_specific.h"
@@ skipping 82 matching lines @@
     // TODO(vadimt): Remove ScopedProfile below once crbug.com/422489 is fixed.
     tracked_objects::ScopedProfile tracking_profile(
         FROM_HERE_WITH_EXPLICIT_FUNCTION(
             "422489 URLRequestSimpleJob::StartAsync 3"));
 
     OnGetDataCompleted(result);
   }
 }
 
 void URLRequestSimpleJob::OnGetDataCompleted(int result) {
+  // TODO(vadimt): Remove ScopedProfile below once crbug.com/422489 is fixed.
+  tracked_objects::ScopedProfile tracking_profile(
+      FROM_HERE_WITH_EXPLICIT_FUNCTION(
+          "422489 URLRequestSimpleJob::OnGetDataCompleted"));
+
   if (result == OK) {
     // Notify that the headers are complete
     if (!byte_range_.ComputeBounds(data_.size())) {
       NotifyDone(URLRequestStatus(URLRequestStatus::FAILED,
                  ERR_REQUEST_RANGE_NOT_SATISFIABLE));
       return;
     }
 
     data_offset_ = byte_range_.first_byte_position();
     int remaining_bytes = byte_range_.last_byte_position() -
         byte_range_.first_byte_position() + 1;
     set_expected_content_size(remaining_bytes);
     NotifyHeadersComplete();
   } else {
     NotifyStartError(URLRequestStatus(URLRequestStatus::FAILED, result));
   }
 }
 
 }  // namespace net