Fix trace parameter showing gibberish.

content/browser/download/mhtml_generation_manager.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 "content/browser/download/mhtml_generation_manager.h"
 
 #include <map>
 #include <queue>
 #include <utility>
 
@@ skipping 376 matching lines @@
 }
 
 void MHTMLGenerationManager::SaveMHTML(WebContents* web_contents,
                                        const MHTMLGenerationParams& params,
                                        const GenerateMHTMLCallback& callback) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 
   Job* job = NewJob(web_contents, params, callback);
   TRACE_EVENT_NESTABLE_ASYNC_BEGIN2(
       "page-serialization", "SavingMhtmlJob", job, "url",
-      web_contents->GetLastCommittedURL().possibly_invalid_spec().c_str(),
-      "file", params.file_path.value().c_str());
+      web_contents->GetLastCommittedURL().possibly_invalid_spec(),
+      "file", params.file_path.AsUTF8Unsafe());
 
   BrowserThread::PostTaskAndReplyWithResult(
       BrowserThread::FILE, FROM_HERE,
       base::Bind(&MHTMLGenerationManager::CreateFile, params.file_path),
       base::Bind(&MHTMLGenerationManager::OnFileAvailable,
                  base::Unretained(this),  // Safe b/c |this| is a singleton.
                  job->id()));
 }
 
 void MHTMLGenerationManager::OnSerializeAsMHTMLResponse(
@@ skipping 121 matching lines @@
   return iter->second;
 }
 
 void MHTMLGenerationManager::RenderProcessExited(Job* job) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
   DCHECK(job);
   JobFinished(job, JobStatus::FAILURE);
 }
 
 }  // namespace content