Make cc::SoftwareImageDecodeController, cc::ResourcePool, and cc::StagingBufferPoo…

components/memory_coordinator/common/client_registry.cc

 // Copyright 2016 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/memory_coordinator/common/client_registry.h"
 
 namespace memory_coordinator {
 
+ClientRegistry* ClientRegistry::instance_ = nullptr;
+
 ClientRegistry::ClientRegistry() : clients_(new ClientList) {}
 
 ClientRegistry::~ClientRegistry() {}
 
 void ClientRegistry::RegisterClient(MemoryCoordinatorClient* client) {
   clients_->AddObserver(client);
 }
 
 void ClientRegistry::UnregisterClient(MemoryCoordinatorClient* client) {
   clients_->RemoveObserver(client);
 }
 
+ClientRegistry* ClientRegistry::GetInstance() {
+  return instance_;
+}
+
+void ClientRegistry::SetInstance(ClientRegistry* instance) {
+  instance_ = instance;
+}
+
 }  // namespace memory_coordinator