Added memory pressure monitor for linux.

base/memory/memory_pressure_monitor_mac.h

Index: base/memory/memory_pressure_monitor_mac.h
diff --git a/base/memory/memory_pressure_monitor_mac.h b/base/memory/memory_pressure_monitor_mac.h
deleted file mode 100644
index 8d4c26a55f0c0ded0a8260afea68d49549ea940f..0000000000000000000000000000000000000000
--- a/base/memory/memory_pressure_monitor_mac.h
+++ /dev/null
@@ -1,63 +0,0 @@
-// 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 BASE_MEMORY_MEMORY_PRESSURE_MONITOR_MAC_H_
-#define BASE_MEMORY_MEMORY_PRESSURE_MONITOR_MAC_H_
-
-#include <dispatch/dispatch.h>
-
-#include "base/base_export.h"
-#include "base/memory/memory_pressure_listener.h"
-#include "base/memory/memory_pressure_monitor.h"
-
-// The following was added to <dispatch/source.h> after 10.8.
-// TODO(shrike): Remove the DISPATCH_MEMORYPRESSURE_NORMAL ifndef once builders
-// reach 10.9 or higher.
-#ifndef DISPATCH_MEMORYPRESSURE_NORMAL
-
-#define DISPATCH_MEMORYPRESSURE_NORMAL    0x01
-#define DISPATCH_MEMORYPRESSURE_WARN      0x02
-#define DISPATCH_MEMORYPRESSURE_CRITICAL  0x04
-
-#endif  // DISPATCH_MEMORYPRESSURE_NORMAL
-
-namespace base {
-namespace mac {
-
-class TestMemoryPressureMonitor;
-
-struct DispatchSourceSDeleter {
-  void operator()(dispatch_source_s* ptr) {
-    dispatch_source_cancel(ptr);
-    dispatch_release(ptr);
-  }
-};
-
-// Declares the interface for the Mac MemoryPressureMonitor, which reports
-// memory pressure events and status.
-class BASE_EXPORT MemoryPressureMonitor : public base::MemoryPressureMonitor {
- public:
-  MemoryPressureMonitor();
-  ~MemoryPressureMonitor() override;
-
-  // Returns the currently-observed memory pressure.
-  MemoryPressureLevel GetCurrentPressureLevel() const override;
-
- private:
-  friend TestMemoryPressureMonitor;
-
-  static MemoryPressureLevel
-      MemoryPressureLevelForMacMemoryPressure(int mac_memory_pressure);
-  static void NotifyMemoryPressureChanged(dispatch_source_s* event_source);
-
-  scoped_ptr<dispatch_source_s, DispatchSourceSDeleter>
-      memory_level_event_source_;
-
-  DISALLOW_COPY_AND_ASSIGN(MemoryPressureMonitor);
-};
-
-}  // namespace mac
-}  // namespace base
-
-#endif  // BASE_MEMORY_MEMORY_PRESSURE_MONITOR_MAC_H_