Renamed DefaultPrefStore into InMemoryPrefStore because it can be used in further contexts.

chrome/browser/prefs/in_memory_pref_store.cc

+// Copyright (c) 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.
+
+#include "chrome/browser/prefs/in_memory_pref_store.h"
+
+#include "base/values.h"
+
+InMemoryPrefStore::InMemoryPrefStore() : prefs_(new DictionaryValue()) {
+}
+
+InMemoryPrefStore::~InMemoryPrefStore() {
+}
+
+DictionaryValue* InMemoryPrefStore::prefs() const {
+  return prefs_.get();
+}
+
+PrefStore::PrefReadError InMemoryPrefStore::ReadPrefs() {
+  return PrefStore::PREF_READ_ERROR_NONE;
+}