Rename OS-specific MemoryPressureMonitor implementations.

base/mac/memory_pressure_monitor_mac.cc

-// 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.
-
-#include "base/mac/memory_pressure_monitor_mac.h"
-
-#include <dlfcn.h>
-#include <sys/sysctl.h>
-
-#include "base/mac/mac_util.h"
-
-namespace base {
-
-MemoryPressureListener::MemoryPressureLevel
-MemoryPressureMonitorMac::MemoryPressureLevelForMacMemoryPressure(
-    int mac_memory_pressure) {
-  switch (mac_memory_pressure) {
-    case DISPATCH_MEMORYPRESSURE_NORMAL:
-      return MemoryPressureListener::MEMORY_PRESSURE_LEVEL_NONE;
-    case DISPATCH_MEMORYPRESSURE_WARN:
-      return MemoryPressureListener::MEMORY_PRESSURE_LEVEL_MODERATE;
-    case DISPATCH_MEMORYPRESSURE_CRITICAL:
-      return MemoryPressureListener::MEMORY_PRESSURE_LEVEL_CRITICAL;
-  }
-  return MemoryPressureListener::MEMORY_PRESSURE_LEVEL_NONE;
-}
-
-void MemoryPressureMonitorMac::NotifyMemoryPressureChanged(
-    dispatch_source_s* event_source) {
-  int mac_memory_pressure = dispatch_source_get_data(event_source);
-  MemoryPressureListener::MemoryPressureLevel memory_pressure_level =
-      MemoryPressureLevelForMacMemoryPressure(mac_memory_pressure);
-  MemoryPressureListener::NotifyMemoryPressure(memory_pressure_level);
-}
-
-MemoryPressureMonitorMac::MemoryPressureMonitorMac()
-  : memory_level_event_source_(nullptr) {
-  // _dispatch_source_type_memorypressure is not available prior to 10.9.
-  dispatch_source_type_t dispatch_source_memorypressure =
-      static_cast<dispatch_source_type_t>
-          (dlsym(RTLD_NEXT, "_dispatch_source_type_memorypressure"));
-  if (dispatch_source_memorypressure) {
-    // The MemoryPressureListener doesn't want to know about transitions to
-    // MEMORY_PRESSURE_LEVEL_NONE so don't watch for
-    // DISPATCH_MEMORYPRESSURE_NORMAL notifications.
-    memory_level_event_source_.reset(
-        dispatch_source_create(dispatch_source_memorypressure, 0,
-                               DISPATCH_MEMORYPRESSURE_WARN |
-                                   DISPATCH_MEMORYPRESSURE_CRITICAL,
-                               dispatch_get_global_queue(
-                                   DISPATCH_QUEUE_PRIORITY_DEFAULT, 0)));
-
-    dispatch_source_set_event_handler(memory_level_event_source_.get(), ^{
-        NotifyMemoryPressureChanged(memory_level_event_source_.get());
-    });
-    dispatch_retain(memory_level_event_source_.get());
-    dispatch_resume(memory_level_event_source_.get());
-  }
-}
-
-MemoryPressureMonitorMac::~MemoryPressureMonitorMac() {
-}
-
-MemoryPressureListener::MemoryPressureLevel
-MemoryPressureMonitorMac::GetCurrentPressureLevel() const {
-  if (base::mac::IsOSMountainLionOrEarlier()) {
-    return MemoryPressureListener::MEMORY_PRESSURE_LEVEL_NONE;
-  }
-  int mac_memory_pressure;
-  size_t length = sizeof(int);
-  sysctlbyname("kern.memorystatus_vm_pressure_level", &mac_memory_pressure,
-               &length, nullptr, 0);
-  return MemoryPressureLevelForMacMemoryPressure(mac_memory_pressure);
-}
-
-}  // namespace base