Clean up after each MemoryCoordinatorImpl test

base/memory/memory_coordinator_proxy.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 "base/memory/memory_coordinator_proxy.h"
 
 namespace base {
 
 namespace {
 
 MemoryCoordinator* g_memory_coordinator = nullptr;
 
 }  // namespace
 
 MemoryCoordinatorProxy::MemoryCoordinatorProxy() {
 }
 
 MemoryCoordinatorProxy::~MemoryCoordinatorProxy() {
 }
 
 // static
 MemoryCoordinatorProxy* MemoryCoordinatorProxy::GetInstance() {
   return Singleton<base::MemoryCoordinatorProxy>::get();
 }
 
 // static
 void MemoryCoordinatorProxy::SetMemoryCoordinator(
     MemoryCoordinator* coordinator) {
-  DCHECK(!g_memory_coordinator);
+  DCHECK(!g_memory_coordinator || !coordinator);
   g_memory_coordinator = coordinator;
 }
 
 MemoryState MemoryCoordinatorProxy::GetCurrentMemoryState() const {
   if (!g_memory_coordinator)
     return MemoryState::NORMAL;
   return g_memory_coordinator->GetCurrentMemoryState();
 }
 
 void MemoryCoordinatorProxy::SetCurrentMemoryStateForTesting(
     MemoryState memory_state) {
   DCHECK(g_memory_coordinator);
   g_memory_coordinator->SetCurrentMemoryStateForTesting(memory_state);
 }
 
 }  // namespace base