Disk Cache: Replace the worker pool with a sequenced worker pool (posix).

net/disk_cache/backend_impl.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 "net/disk_cache/backend_impl.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/file_util.h"
 #include "base/files/file_path.h"
@@ skipping 319 matching lines @@
 
   if (init_) {
     StoreStats();
     if (data_)
       data_->header.crash = 0;
 
     if (user_flags_ & kNoRandom) {
       // This is a net_unittest, verify that we are not 'leaking' entries.
       File::WaitForPendingIO(&num_pending_io_);
       DCHECK(!num_refs_);
-    } else {
-      File::DropPendingIO();
     }
   }
   block_files_.CloseFiles();
   FlushIndex();
   index_ = NULL;
   ptr_factory_.InvalidateWeakPtrs();
   done_.Signal();
 }
 
 // ------------------------------------------------------------------------
@@ skipping 1759 matching lines @@
     if (total_memory > kMaxBuffersSize || total_memory <= 0)
       total_memory = kMaxBuffersSize;
 
     done = true;
   }
 
   return static_cast<int>(total_memory);
 }
 
 }  // namespace disk_cache