Remove dependency of PrefSyncableService on Profile.

chrome/browser/prefs/pref_service_syncable_util.h

Index: chrome/browser/prefs/pref_service_syncable_util.h
diff --git a/chrome/browser/prefs/pref_service_syncable_util.h b/chrome/browser/prefs/pref_service_syncable_util.h
new file mode 100644
index 0000000000000000000000000000000000000000..71dd077448865e37841b364d893b9971483607f5
--- /dev/null
+++ b/chrome/browser/prefs/pref_service_syncable_util.h
@@ -0,0 +1,23 @@
+// Copyright 2015 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_PREF_SERVICE_SYNCABLE_UTIL_H_
+#define CHROME_BROWSER_PREFS_PREF_SERVICE_SYNCABLE_UTIL_H_
+
+class PrefServiceSyncable;
+class Profile;
+
+// PrefServiceSyncable is a PrefService with added integration for
+// sync, and knowledge of how to create an incognito
+// PrefService. For code that does not need to know about the sync
+// integration, you should use only the plain PrefService type.
+//
+// For this reason, Profile does not expose an accessor for the
+// PrefServiceSyncable type. Instead, you can use the utilities
+// below to retrieve the PrefServiceSyncable (or its incognito
+// version) from a Profile.
+PrefServiceSyncable* PrefServiceSyncableFromProfile(Profile* profile);
+PrefServiceSyncable* PrefServiceSyncableIncognitoFromProfile(Profile* profile);
+
+#endif  // CHROME_BROWSER_PREFS_PREF_SERVICE_SYNCABLE_UTIL_H_