Update from https://crrev.com/303153

net/disk_cache/simple/simple_index_file.cc

 // Copyright (c) 2013 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 "net/disk_cache/simple/simple_index_file.h"
 
 #include <vector>
 
 #include "base/files/file.h"
 #include "base/files/file_util.h"
@@ skipping 260 matching lines @@
   base::Closure task = base::Bind(&SimpleIndexFile::SyncLoadIndexEntries,
                                   cache_type_,
                                   cache_last_modified, cache_directory_,
                                   index_file_, out_result);
   worker_pool_->PostTaskAndReply(FROM_HERE, task, callback);
 }
 
 void SimpleIndexFile::WriteToDisk(const SimpleIndex::EntrySet& entry_set,
                                   uint64 cache_size,
                                   const base::TimeTicks& start,
-                                  bool app_on_background) {
+                                  bool app_on_background,
+                                  const base::Closure& callback) {
   IndexMetadata index_metadata(entry_set.size(), cache_size);
   scoped_ptr<Pickle> pickle = Serialize(index_metadata, entry_set);
-  cache_thread_->PostTask(FROM_HERE,
-                          base::Bind(&SimpleIndexFile::SyncWriteToDisk,
-                                     cache_type_,
-                                     cache_directory_,
-                                     index_file_,
-                                     temp_index_file_,
-                                     base::Passed(&pickle),
-                                     base::TimeTicks::Now(),
-                                     app_on_background));
+  base::Closure task =
+      base::Bind(&SimpleIndexFile::SyncWriteToDisk,
+                 cache_type_, cache_directory_, index_file_, temp_index_file_,
+                 base::Passed(&pickle), start, app_on_background);
+  if (callback.is_null())
+    cache_thread_->PostTask(FROM_HERE, task);
+  else
+    cache_thread_->PostTaskAndReply(FROM_HERE, task, callback);
 }
 
 // static
 void SimpleIndexFile::SyncLoadIndexEntries(
     net::CacheType cache_type,
     base::Time cache_last_modified,
     const base::FilePath& cache_directory,
     const base::FilePath& index_file_path,
     SimpleIndexLoadResult* out_result) {
   // Load the index and find its age.
@@ skipping 170 matching lines @@
 bool SimpleIndexFile::LegacyIsIndexFileStale(
     base::Time cache_last_modified,
     const base::FilePath& index_file_path) {
   base::Time index_mtime;
   if (!simple_util::GetMTime(index_file_path, &index_mtime))
     return true;
   return index_mtime < cache_last_modified;
 }
 
 }  // namespace disk_cache