Refactor MemoryCoordinatorProxy

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"
 
+#include "base/atomicops.h"
+
 namespace base {
 
+namespace {
+
+subtle::AtomicWord g_memory_coordinator = 0;

[dcheng, 2017/02/20 03:07:21]

Is it necessary to use atomics? The base::Callback version of this interface
didn't use them.

[bashi, 2017/02/20 03:16:59]

Probably it isn't necessary to use atomics. I just felt that it's a bit unsafe
to set a static variable without guards. Should we remove atomics?

+
+inline MemoryCoordinator* GetMemoryCoordinator() {
+  subtle::AtomicWord coordinator =
+      base::subtle::Acquire_Load(&g_memory_coordinator);
+  return reinterpret_cast<MemoryCoordinator*>(coordinator);
+}
+
+}  // namespace
+
 MemoryCoordinatorProxy::MemoryCoordinatorProxy() {
 }
 
 MemoryCoordinatorProxy::~MemoryCoordinatorProxy() {
 }
 
+// static
 MemoryCoordinatorProxy* MemoryCoordinatorProxy::GetInstance() {
   return Singleton<base::MemoryCoordinatorProxy>::get();
 }
 
+// static
+void MemoryCoordinatorProxy::SetMemoryCoordinator(
+    MemoryCoordinator* coordinator) {
+  base::subtle::Release_Store(
+      &g_memory_coordinator, reinterpret_cast<subtle::AtomicWord>(coordinator));
+}
+
 MemoryState MemoryCoordinatorProxy::GetCurrentMemoryState() const {
-  if (!getter_callback_)
+  auto* coordinator = GetMemoryCoordinator();
+  if (!coordinator)
     return MemoryState::NORMAL;
-  return getter_callback_.Run();
+  return coordinator->GetCurrentMemoryState();
 }
 
 void MemoryCoordinatorProxy::SetCurrentMemoryStateForTesting(
     MemoryState memory_state) {
-  DCHECK(setter_callback_);
-  setter_callback_.Run(memory_state);
-}
-
-void MemoryCoordinatorProxy::SetGetCurrentMemoryStateCallback(
-    GetCurrentMemoryStateCallback callback) {
-  getter_callback_ = callback;
-}
-
-void MemoryCoordinatorProxy::SetSetCurrentMemoryStateForTestingCallback(
-    SetCurrentMemoryStateCallback callback) {
-  setter_callback_ = callback;
+  auto* coordinator = GetMemoryCoordinator();
+  DCHECK(coordinator);
+  coordinator->SetCurrentMemoryStateForTesting(memory_state);
 }
 
 }  // namespace base