Revert "Revert the disk_cache change part of http://codereview.chromium.org/9035012"

net/disk_cache/backend_impl.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 "net/disk_cache/backend_impl.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/file_path.h"
 #include "base/file_util.h"
@@ skipping 69 matching lines @@
 // Returns a fully qualified name from path and name, using a given name prefix
 // and index number. For instance, if the arguments are "/foo", "bar" and 5, it
 // will return "/foo/old_bar_005".
 FilePath GetPrefixedName(const FilePath& path, const std::string& name,
                          int index) {
   std::string tmp = base::StringPrintf("%s%s_%03d", "old_",
                                        name.c_str(), index);
   return path.AppendASCII(tmp);
 }
 
-// This is a simple Task to cleanup old caches.
-class CleanupTask : public Task {
- public:
-  CleanupTask(const FilePath& path, const std::string& name)
-      : path_(path), name_(name) {}
-
-  virtual void Run();
-
- private:
-  FilePath path_;
-  std::string name_;
-  DISALLOW_COPY_AND_ASSIGN(CleanupTask);
-};
-
-void CleanupTask::Run() {
+// This is a simple callback to cleanup old caches.
+void CleanupCallback(const FilePath& path, const std::string& name) {
   for (int i = 0; i < kMaxOldFolders; i++) {
-    FilePath to_delete = GetPrefixedName(path_, name_, i);
+    FilePath to_delete = GetPrefixedName(path, name, i);
     disk_cache::DeleteCache(to_delete, true);
   }
 }
 
 // Returns a full path to rename the current cache, in order to delete it. path
 // is the current folder location, and name is the current folder name.
 FilePath GetTempCacheName(const FilePath& path, const std::string& name) {
   // We'll attempt to have up to kMaxOldFolders folders for deletion.
   for (int i = 0; i < kMaxOldFolders; i++) {
     FilePath to_delete = GetPrefixedName(path, name, i);
@@ skipping 24 matching lines @@
   if (to_delete.empty()) {
     LOG(ERROR) << "Unable to get another cache folder";
     return false;
   }
 
   if (!disk_cache::MoveCache(full_path, to_delete)) {
     LOG(ERROR) << "Unable to move cache folder";
     return false;
   }
 
-  base::WorkerPool::PostTask(FROM_HERE, new CleanupTask(path, name_str), true);
+  base::WorkerPool::PostTask(
+      FROM_HERE, base::Bind(&CleanupCallback, path, name_str), true);
   return true;
 }
 
 // Initializes the field trial structures to allow performance measurements
 // for the current cache configuration.
 void SetFieldTrialInfo(int group) {
   static bool first = true;
   if (!first)
     return;
 
@@ skipping 2068 matching lines @@
     if (total_memory > kMaxBuffersSize || total_memory <= 0)
       total_memory = kMaxBuffersSize;
 
     done = true;
   }
 
   return static_cast<int>(total_memory);
 }
 
 }  // namespace disk_cache