Remove knowledge of Chrome-specific SyncableService classes from WebDataService.

base/supports_user_data.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/supports_user_data.h"
 
 namespace base {
 
 SupportsUserData::SupportsUserData() {
   // Harmless to construct on a different thread to subsequent usage.
   thread_checker_.DetachFromThread();
 }
 
+SupportsUserData::~SupportsUserData() {
+  DCHECK(thread_checker_.CalledOnValidThread() || user_data_.empty());
+}
+
 SupportsUserData::Data* SupportsUserData::GetUserData(const void* key) const {
   DCHECK(thread_checker_.CalledOnValidThread());
   DataMap::const_iterator found = user_data_.find(key);
   if (found != user_data_.end())
     return found->second.get();
   return NULL;
 }
 
 void SupportsUserData::SetUserData(const void* key, Data* data) {
   DCHECK(thread_checker_.CalledOnValidThread());
   user_data_[key] = linked_ptr<Data>(data);
 }
 
 void SupportsUserData::RemoveUserData(const void* key) {
   DCHECK(thread_checker_.CalledOnValidThread());
   user_data_.erase(key);
 }
 
 void SupportsUserData::DetachUserDataThread() {
   thread_checker_.DetachFromThread();
 }
 
-SupportsUserData::~SupportsUserData() {
-  DCHECK(thread_checker_.CalledOnValidThread() || user_data_.empty());
-}
-
 }  // namespace base