Introduce per-tab preferences service.

chrome/browser/prefs/per_tab_user_pref_store.h

Index: chrome/browser/prefs/per_tab_user_pref_store.h
diff --git a/chrome/browser/prefs/per_tab_user_pref_store.h b/chrome/browser/prefs/per_tab_user_pref_store.h
new file mode 100644
index 0000000000000000000000000000000000000000..6fd7038dc6b48412135a9fa95bb9d260f7065ccd
--- /dev/null
+++ b/chrome/browser/prefs/per_tab_user_pref_store.h
@@ -0,0 +1,20 @@
+// 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.
+
+#ifndef CHROME_BROWSER_PREFS_PER_TAB_USER_PREF_STORE_H_
+#define CHROME_BROWSER_PREFS_PER_TAB_USER_PREF_STORE_H_
+#pragma once
+
+#include "base/basictypes.h"
+#include "chrome/browser/prefs/overlay_user_pref_store.h"
+
+class PerTabUserPrefStore : public OverlayUserPrefStore {
+ public:
+  explicit PerTabUserPrefStore(PersistentPrefStore* underlay);
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(PerTabUserPrefStore);
+};
+
+#endif  // CHROME_BROWSER_PREFS_PER_TAB_USER_PREF_STORE_H_