Turn on file access checks on Win.

net/url_request/url_request_file_job.cc

 // Copyright (c) 2006-2010 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.
 
 // For loading files, we make use of overlapped i/o to ensure that reading from
 // the filesystem (e.g., a network filesystem) does not block the calling
 // thread.  An alternative approach would be to use a background thread or pool
 // of threads, but it seems better to leverage the operating system's ability
 // to do background file reads for us.
 //
@@ skipping 185 matching lines @@
   DCHECK(encoding_types->empty());
 
   // Bug 9936 - .svgz files needs to be decompressed.
   if (LowerCaseEqualsASCII(file_path_.Extension(), ".svgz"))
     encoding_types->push_back(Filter::FILTER_TYPE_GZIP);
 
   return !encoding_types->empty();
 }
 
 bool URLRequestFileJob::GetMimeType(std::string* mime_type) const {
+  // URL requests should not block on the disk!  On Windows this goes to the
+  // registry.
+  //   http://code.google.com/p/chromium/issues/detail?id=59849
+  base::ThreadRestrictions::ScopedAllowIO allow_io;
   DCHECK(request_);
   return net::GetMimeTypeFromFile(file_path_, mime_type);
 }
 
 void URLRequestFileJob::SetExtraRequestHeaders(
     const net::HttpRequestHeaders& headers) {
   std::string range_header;
   if (headers.GetHeader(net::HttpRequestHeaders::kRange, &range_header)) {
     // We only care about "Range" header here.
     std::vector<net::HttpByteRange> ranges;
@@ skipping 29 matching lines @@
   // trailing slash.
   // If a directory does not exist, we return ERR_FILE_NOT_FOUND. Otherwise,
   // we will append trailing slash and redirect to FileDirJob.
   // A special case is "\" on Windows. We should resolve as invalid.
   // However, Windows resolves "\" to "C:\", thus reports it as existent.
   // So what happens is we append it with trailing slash and redirect it to
   // FileDirJob where it is resolved as invalid.
   if (!exists) {
     rv = net::ERR_FILE_NOT_FOUND;
   } else if (!is_directory_) {
+    // URL requests should not block on the disk!
+    //   http://code.google.com/p/chromium/issues/detail?id=59849
+    base::ThreadRestrictions::ScopedAllowIO allow_io;
+
     int flags = base::PLATFORM_FILE_OPEN |
                 base::PLATFORM_FILE_READ |
                 base::PLATFORM_FILE_ASYNC;
     rv = stream_.Open(file_path_, flags);
   }
 
   if (rv != net::OK) {
     NotifyDone(URLRequestStatus(URLRequestStatus::FAILED, rv));
     return;
   }
@@ skipping 66 matching lines @@
   if (!resolved)
     return false;
 
   *location = net::FilePathToFileURL(new_path);
   *http_status_code = 301;
   return true;
 #else
   return false;
 #endif
 }