Replace deprecated base::NonThreadSafe in components/policy in favor of SequenceChecker.

components/policy/core/common/schema_registry.cc

 // Copyright 2013 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 "components/policy/core/common/schema_registry.h"
 
 #include "base/logging.h"
 #include "extensions/features/features.h"
 
 namespace policy {
 
 SchemaRegistry::Observer::~Observer() {}
 
 SchemaRegistry::InternalObserver::~InternalObserver() {}
 
 SchemaRegistry::SchemaRegistry() : schema_map_(new SchemaMap) {
   for (int i = 0; i < POLICY_DOMAIN_SIZE; ++i)
     domains_ready_[i] = false;
 #if !BUILDFLAG(ENABLE_EXTENSIONS)
   SetExtensionsDomainsReady();
 #endif
 }
 
 SchemaRegistry::~SchemaRegistry() {
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);

[emaxx, 2017/05/30 10:54:39]

(note for myself) We need to also add the DCHECKs into other methods of this
class. Filed a bug https://crbug.com/727645 for that.

   for (auto& observer : internal_observers_)
     observer.OnSchemaRegistryShuttingDown(this);
 }
 
 void SchemaRegistry::RegisterComponent(const PolicyNamespace& ns,
                                        const Schema& schema) {
   ComponentMap map;
   map[ns.component_id] = schema;
   RegisterComponents(ns.domain, map);
 }
@@ skipping 209 matching lines @@
   wrapped_ = NULL;
   // Keep serving the same |schema_map_|.
 }
 
 void ForwardingSchemaRegistry::UpdateReadiness() {
   if (wrapped_->IsReady())
     SetAllDomainsReady();
 }
 
 }  // namespace policy