Introduce MemoryCoordinatorProxy in base

base/memory/memory_coordinator_proxy.h

+// 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.
+
+#ifndef BASE_MEMORY_MEMORY_COORDINATOR_PROXY_H_
+#define BASE_MEMORY_MEMORY_COORDINATOR_PROXY_H_
+
+#include "base/base_export.h"
+#include "base/callback.h"
+#include "base/memory/memory_coordinator_client.h"
+#include "base/memory/singleton.h"
+
+namespace base {
+
+// The proxy of MemoryCoordinator to be accessed from components that is not
+// in content/browser e.g. net.
+class BASE_EXPORT MemoryCoordinatorProxy {
+ public:
+  using GetCurrentMemoryStateCallback = base::Callback<MemoryState()>;
+
+  static MemoryCoordinatorProxy* GetInstance();
+
+  // Returns the current memory state.
+  MemoryState GetCurrentMemoryState() const;
+
+  // Sets state-getter callback.
+  void SetGetCurrentMemoryStateCallback(GetCurrentMemoryStateCallback callback);
+
+ private:
+  friend struct base::DefaultSingletonTraits<MemoryCoordinatorProxy>;
+
+  MemoryCoordinatorProxy();
+  virtual ~MemoryCoordinatorProxy();
+
+  GetCurrentMemoryStateCallback callback_;
+
+  DISALLOW_COPY_AND_ASSIGN(MemoryCoordinatorProxy);
+};
+
+}  // namespace base
+
+#endif  // BASE_MEMORY_MEMORY_COORDINATOR_PROXY_H_