Provide renderers with memory pressure signals.

content/browser/memory/memory_pressure_controller.h

-// Copyright 2015 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 CONTENT_BROWSER_MEMORY_MEMORY_PRESSURE_CONTROLLER_H_
-#define CONTENT_BROWSER_MEMORY_MEMORY_PRESSURE_CONTROLLER_H_
-
-#include <map>
-
-#include "base/callback.h"
-#include "base/macros.h"
-#include "base/memory/memory_pressure_listener.h"
-#include "base/memory/singleton.h"
-#include "content/common/content_export.h"
-
-namespace content {
-
-class BrowserChildProcessHost;
-class MemoryMessageFilter;
-class RenderProcessHost;
-
-class CONTENT_EXPORT MemoryPressureController {
- public:
-  // These methods must be called on the IO thread.
-  void OnMemoryMessageFilterAdded(MemoryMessageFilter* filter);
-  void OnMemoryMessageFilterRemoved(MemoryMessageFilter* filter);
-
-  // These methods can be called from any thread.
-  void SetPressureNotificationsSuppressedInAllProcesses(bool suppressed);
-  void SimulatePressureNotificationInAllProcesses(
-      base::MemoryPressureListener::MemoryPressureLevel level);
-  void SendPressureNotification(
-      const BrowserChildProcessHost* child_process_host,
-      base::MemoryPressureListener::MemoryPressureLevel level);
-  void SendPressureNotification(
-      const RenderProcessHost* render_process_host,
-      base::MemoryPressureListener::MemoryPressureLevel level);
-
-  // This method can be called from any thread.
-  static MemoryPressureController* GetInstance();
-
- protected:
-  virtual ~MemoryPressureController();
-
- private:
-  friend struct base::DefaultSingletonTraits<MemoryPressureController>;
-
-  MemoryPressureController();
-
-  // Implementation of the various SendPressureNotification methods.
-  void SendPressureNotificationImpl(
-      const void* child_process_host,
-      base::MemoryPressureListener::MemoryPressureLevel level);
-
-  // Map from untyped process host pointers to the associated memory message
-  // filters in the browser process. Always accessed on the IO thread.
-  typedef std::map<const void*, scoped_refptr<MemoryMessageFilter>>
-      MemoryMessageFilterMap;
-  MemoryMessageFilterMap memory_message_filters_;
-
-  DISALLOW_COPY_AND_ASSIGN(MemoryPressureController);
-};
-
-}  // namespace content
-
-#endif  // CONTENT_BROWSER_MEMORY_MEMORY_PRESSURE_CONTROLLER_H_