Adding instrumentation to locate the source of jankiness.

chrome/browser/predictors/resource_prefetcher.cc

 // Copyright 2014 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/predictors/resource_prefetcher.h"
 
 #include <iterator>
 
+#include "base/profiler/scoped_tracker.h"
 #include "base/stl_util.h"
 #include "content/public/browser/browser_thread.h"
 #include "net/base/io_buffer.h"
 #include "net/base/request_priority.h"
 #include "net/url_request/url_request_context.h"
 
 namespace {
 
 // The size of the buffer used to read the resource.
 static const size_t kResourceBufferSizeBytes = 50000;
@@ skipping 191 matching lines @@
   FinishRequest(request, Request::PREFETCH_STATUS_CERT_REQUIRED);
 }
 
 void ResourcePrefetcher::OnSSLCertificateError(net::URLRequest* request,
                                                const net::SSLInfo& ssl_info,
                                                bool fatal) {
   FinishRequest(request, Request::PREFETCH_STATUS_CERT_ERROR);
 }
 
 void ResourcePrefetcher::OnResponseStarted(net::URLRequest* request) {
+  // TODO(vadimt): Remove ScopedTracker below once crbug.com/423948 is fixed.
+  tracked_objects::ScopedTracker tracking_profile(
+      FROM_HERE_WITH_EXPLICIT_FUNCTION(
+          "423948 ResourcePrefetcher::OnResponseStarted"));
+
   if (request->status().error()) {
     FinishRequest(request, Request::PREFETCH_STATUS_FAILED);
     return;
   }
 
   // TODO(shishir): Do not read cached entries, or ones that are not cacheable.
   ReadFullResponse(request);
 }
 
 void ResourcePrefetcher::OnReadCompleted(net::URLRequest* request,
                                          int bytes_read) {
+  // TODO(vadimt): Remove ScopedTracker below once crbug.com/423948 is fixed.
+  tracked_objects::ScopedTracker tracking_profile(
+      FROM_HERE_WITH_EXPLICIT_FUNCTION(
+          "423948 ResourcePrefetcher::OnReadCompleted"));
+
   if (request->status().error()) {
     FinishRequest(request, Request::PREFETCH_STATUS_FAILED);
     return;
   }
 
   if (ShouldContinueReadingRequest(request, bytes_read))
     ReadFullResponse(request);
 }
 
 }  // namespace predictors