Get rid of trivial IncognitoUserPrefStore and PerTabUserPrefStore.

chrome/browser/prefs/incognito_user_pref_store.cc

Index: chrome/browser/prefs/incognito_user_pref_store.cc
diff --git a/chrome/browser/prefs/incognito_user_pref_store.cc b/chrome/browser/prefs/incognito_user_pref_store.cc
deleted file mode 100644
index c979cce5845fb76dc2711e13e5bd36a343465c63..0000000000000000000000000000000000000000
--- a/chrome/browser/prefs/incognito_user_pref_store.cc
+++ /dev/null
@@ -1,14 +0,0 @@
-// 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 "chrome/browser/prefs/incognito_user_pref_store.h"
-#include "chrome/common/pref_names.h"
-
-IncognitoUserPrefStore::IncognitoUserPrefStore(PersistentPrefStore* underlay)
-    : OverlayUserPrefStore(underlay) {
-  // List of keys that cannot be changed in the user prefs file by the incognito
-  // profile.  All preferences that store information about the browsing history
-  // or behavior of the user should have this property.
-  RegisterOverlayProperty(prefs::kBrowserWindowPlacement);
-}