Print Preview: Add some debug logging so one can time when print preview operations starts/finishes.

chrome/browser/ui/webui/print_preview_ui.cc

 // Copyright (c) 2011 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/ui/webui/print_preview_ui.h"
 
 #include "base/values.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/webui/print_preview_handler.h"
 #include "chrome/browser/ui/webui/print_preview_ui_html_source.h"
@@ skipping 20 matching lines @@
 
 void PrintPreviewUI::OnInitiatorTabClosed(
     const std::string& initiator_url) {
   StringValue initiator_tab_url(initiator_url);
   CallJavascriptFunction("onInitiatorTabClosed", initiator_tab_url);
 }
 
 void PrintPreviewUI::OnPreviewDataIsAvailable(int expected_pages_count,
                                               const string16& job_title,
                                               bool modifiable) {
+  VLOG(1) << "Print preview request finished with "
+          << expected_pages_count << " pages";
   FundamentalValue pages_count(expected_pages_count);
   StringValue title(job_title);
   FundamentalValue is_preview_modifiable(modifiable);
   CallJavascriptFunction("updatePrintPreview", pages_count, title,
                          is_preview_modifiable);
 }