Memory-monitor for Mac.

content/browser/memory/memory_monitor_mac.h

+// Copyright (c) 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 CONTENT_BROWSER_MEMORY_MEMORY_MONITOR_MAC_H_
+#define CONTENT_BROWSER_MEMORY_MEMORY_MONITOR_MAC_H_
+
+#include "content/browser/memory/memory_monitor.h"
+#include "content/common/content_export.h"
+
+namespace content {
+
+// A memory monitor for the Mac platform.
+class CONTENT_EXPORT MemoryMonitorMac : public MemoryMonitor {
+ public:
+  MemoryMonitorMac(MemoryMonitorDelegate* delegate,
+                   base::TimeDelta poll_interval);
+  ~MemoryMonitorMac() override;
+
+  // MemoryMonitor:
+  int GetFreeMemoryUntilCriticalMB() override;
+
+  // Factory function to create an instance of this class.
+  static std::unique_ptr<MemoryMonitorMac> Create(
+      MemoryMonitorDelegate* delegate,
+      base::TimeDelta poll_interval);
+
+ private:
+  // The delegate to be used for retrieving system memory information. Used as a
+  // testing seam.
+  MemoryMonitorDelegate* delegate_;
+
+  // The poll-interval amount by which |critical_free_mb_| increase.
+  const int64_t poll_interval_adjustment_mb_;
+
+  // The threshold of free memory that is considered "critical". This value is
+  // determined dynamically via system "memory pressure" events.
+  int critical_free_mb_;
+};
+
+// A delegate with extra methods required to support Mac.
+class CONTENT_EXPORT MemoryMonitorMacDelegate : public MemoryMonitorDelegate {
+ public:
+  static MemoryMonitorMacDelegate* GetInstance();
+
+  // Returns system memory-pressure information. According to dispatch/source.h
+  // the returned integer values are:
+  //   DISPATCH_MEMORYPRESSURE_NORMAL: System has sufficient memory available.
+  //   DISPATCH_MEMORYPRESSURE_WARN: System memory is getting low.
+  //   DISPATCH_MEMORYPRESSURE_CRITICAL: System has to swap or kill processes.
+  bool GetSystemMemoryPressure(int* mem_pressure) override;
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_MEMORY_MEMORY_MONITOR_MAC_H_