Adding instrumentation to locate the source of jankiness.

components/translate/core/browser/translate_script.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 "components/translate/core/browser/translate_script.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "base/message_loop/message_loop.h"
+#include "base/profiler/scoped_profile.h"
 #include "base/strings/string_piece.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
 #include "components/translate/core/browser/translate_url_fetcher.h"
 #include "components/translate/core/browser/translate_url_util.h"
 #include "components/translate/core/common/translate_switches.h"
 #include "components/translate/core/common/translate_util.h"
 #include "google_apis/google_api_keys.h"
 #include "grit/components_resources.h"
 #include "net/base/escape.h"
@@ skipping 89 matching lines @@
   fetcher_->set_extra_request_header(kRequestHeader);
   fetcher_->Request(
       translate_script_url,
       base::Bind(&TranslateScript::OnScriptFetchComplete,
                  base::Unretained(this)));
 }
 
 
 void TranslateScript::OnScriptFetchComplete(
     int id, bool success, const std::string& data) {
+  // TODO(vadimt): Remove ScopedProfile below once crbug.com/422577 is fixed.
+  tracked_objects::ScopedProfile tracking_profile(
+      FROM_HERE_WITH_EXPLICIT_FUNCTION(
+          "422577 TranslateScript::OnScriptFetchComplete"));
+
   DCHECK_EQ(kFetcherId, id);
 
   scoped_ptr<const TranslateURLFetcher> delete_ptr(fetcher_.release());
 
   if (success) {
     DCHECK(data_.empty());
     // Insert variable definitions on API Key and security origin.
     data_ = base::StringPrintf("var translateApiKey = '%s';\n",
                                google_apis::GetAPIKey().c_str());
 
@@ skipping 19 matching lines @@
 
   for (RequestCallbackList::iterator it = callback_list_.begin();
        it != callback_list_.end();
        ++it) {
     it->Run(success, data);
   }
   callback_list_.clear();
 }
 
 }  // namespace translate