Make FileStream::Seek async and add FileStream::SeekSync for sync operation

net/disk_cache/entry_unittest.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 "base/basictypes.h"
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/file_util.h"
 #include "base/threading/platform_thread.h"
 #include "base/timer.h"
@@ skipping 1768 matching lines @@
 TEST_F(DiskCacheEntryTest, MemoryOnlyDoomSparseEntry) {
   SetMemoryOnlyMode();
   InitCache();
   DoomSparseEntry();
 }
 
 // A CompletionCallback wrapper that deletes the cache from within the callback.
 // The way an CompletionCallback works means that all tasks (even new ones)
 // are executed by the message loop before returning to the caller so the only
 // way to simulate a race is to execute what we want on the callback.
-class SparseTestCompletionCallback: public TestCompletionCallbackBase {
+class SparseTestCompletionCallback: public net::TestCompletionCallbackBase {
  public:
   explicit SparseTestCompletionCallback(disk_cache::Backend* cache)
       : cache_(cache),
         ALLOW_THIS_IN_INITIALIZER_LIST(callback_(
             base::Bind(&SparseTestCompletionCallback::OnComplete,
                        base::Unretained(this)))) {
   }
 
   const net::CompletionCallback& callback() const { return callback_; }
 
@@ skipping 261 matching lines @@
   store->key_len = 800;
   memset(store->key + key.size(), 'k', sizeof(store->key) - key.size());
   entry_impl->entry()->set_modified();
   entry->Close();
 
   // We have a corrupt entry. Now reload it. We should NOT read beyond the
   // allocated buffer here.
   ASSERT_NE(net::OK, OpenEntry(key, &entry));
   DisableIntegrityCheck();
 }