Thread IO safety: file_util annotated, IO thread blocked from doing IO

chrome/browser/net/url_request_mock_http_job.cc

 // Copyright (c) 2006-2008 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/net/url_request_mock_http_job.h"
 
 #include "base/file_util.h"
 #include "base/message_loop.h"
 #include "base/string_util.h"
+#include "base/thread_restrictions.h"
 #include "base/utf_string_conversions.h"
 #include "chrome/common/url_constants.h"
 #include "net/base/net_util.h"
 #include "net/http/http_response_headers.h"
 #include "net/url_request/url_request_filter.h"
 
 static const char kMockHostname[] = "mock.http";
 static const FilePath::CharType kMockHeaderFileSuffix[] =
     FILE_PATH_LITERAL(".mock-http-headers");
 
@@ skipping 60 matching lines @@
 bool URLRequestMockHTTPJob::IsRedirectResponse(GURL* location,
                                                int* http_status_code) {
   // Override the URLRequestFileJob implementation to invoke the default one
   // based on HttpResponseInfo.
   return URLRequestJob::IsRedirectResponse(location, http_status_code);
 }
 
 // Private const version.
 void URLRequestMockHTTPJob::GetResponseInfoConst(
     net::HttpResponseInfo* info) const {
+  // We have to load our headers from disk, but we only use this class
+  // from tests, so allow these IO operations to happen on any thread.
+  base::ThreadRestrictions::ScopedAllowIO allow_io;
+
   FilePath header_file = FilePath(file_path_.value() + kMockHeaderFileSuffix);
   std::string raw_headers;
   if (!file_util::ReadFileToString(header_file, &raw_headers))
     return;
 
   // ParseRawHeaders expects \0 to end each header line.
   ReplaceSubstringsAfterOffset(&raw_headers, 0, "\n", std::string("\0", 1));
   info->headers = new net::HttpResponseHeaders(raw_headers);
 }
 
 bool URLRequestMockHTTPJob::GetMimeType(std::string* mime_type) const {
   net::HttpResponseInfo info;
   GetResponseInfoConst(&info);
   return info.headers && info.headers->GetMimeType(mime_type);
 }
 
 bool URLRequestMockHTTPJob::GetCharset(std::string* charset) {
   net::HttpResponseInfo info;
   GetResponseInfo(&info);
   return info.headers && info.headers->GetCharset(charset);
 }