Fix free memory calculation.

base/process/process_metrics_ios.cc

Index: base/process/process_metrics_ios.cc
diff --git a/base/process/process_metrics_ios.cc b/base/process/process_metrics_ios.cc
index e6b01192b5965c4a8151e655e5a9833e57676867..e38ac8c24c4101f49c56afd321765b1486c11f56 100644
--- a/base/process/process_metrics_ios.cc
+++ b/base/process/process_metrics_ios.cc
@@ -9,6 +9,7 @@
 #include <stddef.h>
 
 #include "base/logging.h"
+#include "base/mac/scoped_mach_port.h"
 #include "base/memory/ptr_util.h"
 
 namespace base {
@@ -26,7 +27,8 @@ bool GetTaskInfo(task_basic_info_64* task_info_data) {
 
 }  // namespace
 
-SystemMemoryInfoKB::SystemMemoryInfoKB() : total(0), free(0) {}
+SystemMemoryInfoKB::SystemMemoryInfoKB()
+    : total(0), free(0), speculative(0), file_backed(0), purgeable(0) {}

[brucedawson, 2017/03/09 19:17:52]

Consider zeroing these where the variables are declared instead of here - newly
available C++ feature that has been approved for use in Chromium. This would
reduce duplication across platform-specific source files.

[Michael K. (Yandex Team), 2017/03/10 15:53:57]

Done.

 
 SystemMemoryInfoKB::SystemMemoryInfoKB(const SystemMemoryInfoKB& other) =
     default;
@@ -91,11 +93,38 @@ size_t GetSystemCommitCharge() {
   return 0;
 }
 
-// Bytes committed by the system.
 bool GetSystemMemoryInfo(SystemMemoryInfoKB* meminfo) {
-  // Unimplemented. Must enable unittest for IOS when this gets implemented.
-  NOTIMPLEMENTED();
-  return false;
+  struct host_basic_info hostinfo;
+  mach_msg_type_number_t count = HOST_BASIC_INFO_COUNT;
+  base::mac::ScopedMachSendRight host(mach_host_self());
+  int result = host_info(host.get(), HOST_BASIC_INFO,
+                         reinterpret_cast<host_info_t>(&hostinfo), &count);
+  if (result != KERN_SUCCESS)
+    return false;
+
+  DCHECK_EQ(HOST_BASIC_INFO_COUNT, count);
+  meminfo->total = static_cast<int>(hostinfo.max_mem / 1024);
+
+  vm_statistics64_data_t vm_info;
+  count = HOST_VM_INFO64_COUNT;
+
+  if (host_statistics64(host.get(), HOST_VM_INFO64,
+                        reinterpret_cast<host_info64_t>(&vm_info),
+                        &count) != KERN_SUCCESS) {
+    return false;
+  }
+  DCHECK_EQ(HOST_VM_INFO64_COUNT, count);
+
+  meminfo->free = static_cast<int>(
+      (vm_info.free_count - vm_info.speculative_count) * PAGE_SIZE / 1024);
+  meminfo->speculative =
+      static_cast<int>(vm_info.speculative_count * PAGE_SIZE / 1024);
+  meminfo->file_backed =
+      static_cast<int>(vm_info.external_page_count * PAGE_SIZE / 1024);
+  meminfo->purgeable =
+      static_cast<int>(vm_info.purgeable_count * PAGE_SIZE / 1024);
+
+  return true;
 }
 
 }  // namespace base