Fix free memory calculation.

base/sys_info_mac.mm

 // 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.
 
 #include "base/sys_info.h"
 
 #include <ApplicationServices/ApplicationServices.h>
 #include <CoreServices/CoreServices.h>
 #import <Foundation/Foundation.h>
 #include <mach/mach_host.h>
 #include <mach/mach_init.h>
 #include <stddef.h>
 #include <stdint.h>
 #include <sys/sysctl.h>
 #include <sys/types.h>
 
 #include "base/logging.h"
 #include "base/mac/mac_util.h"
 #include "base/mac/scoped_mach_port.h"
 #import "base/mac/sdk_forward_declarations.h"
 #include "base/macros.h"
+#include "base/process/process_metrics.h"
 #include "base/strings/stringprintf.h"
 
 namespace base {
 
 // static
 std::string SysInfo::OperatingSystemName() {
   return "Mac OS X";
 }
 
 // static
@@ skipping 44 matching lines @@
   if (result != KERN_SUCCESS) {
     NOTREACHED();
     return 0;
   }
   DCHECK_EQ(HOST_BASIC_INFO_COUNT, count);
   return static_cast<int64_t>(hostinfo.max_mem);
 }
 
 // static
 int64_t SysInfo::AmountOfAvailablePhysicalMemory() {
-  base::mac::ScopedMachSendRight host(mach_host_self());
-  vm_statistics_data_t vm_info;
-  mach_msg_type_number_t count = HOST_VM_INFO_COUNT;
-
-  if (host_statistics(host.get(),
-                      HOST_VM_INFO,
-                      reinterpret_cast<host_info_t>(&vm_info),
-                      &count) != KERN_SUCCESS) {
+  SystemMemoryInfoKB info;
+  if (!GetSystemMemoryInfo(&info)) {
     NOTREACHED();
     return 0;
   }
-
-  return static_cast<int64_t>(vm_info.free_count - vm_info.speculative_count) *
-         PAGE_SIZE;
+  // We should add inactive file-backed memory also but there is no such
+  // information from Mac OS unfortunately.
+  return static_cast<int64_t>(info.free + info.speculative) * 1024;
 }
 
 // static
 std::string SysInfo::CPUModelName() {
   char name[256];
   size_t len = arraysize(name);
   if (sysctlbyname("machdep.cpu.brand_string", &name, &len, NULL, 0) == 0)
     return name;
   return std::string();
 }
 
 std::string SysInfo::HardwareModelName() {
   char model[256];
   size_t len = sizeof(model);
   if (sysctlbyname("hw.model", model, &len, NULL, 0) == 0)
     return std::string(model, 0, len);
   return std::string();
 }
 
 }  // namespace base