Fix some potential Mach port leaks from mach_host_self using a new ScopedMachPort class.

base/sys_info_ios.mm

Index: base/sys_info_ios.mm
diff --git a/base/sys_info_ios.mm b/base/sys_info_ios.mm
index 8b1ffd4521192f0f9db7e9c2b3b6621a4e6d1838..1ee0e545e3ee5054b10e7f7858d78f2577fe4b1b 100644
--- a/base/sys_info_ios.mm
+++ b/base/sys_info_ios.mm
@@ -10,6 +10,7 @@
 #include <sys/types.h>
 
 #include "base/logging.h"
+#include "base/mac/scoped_mach_port.h"
 #include "base/mac/scoped_nsautorelease_pool.h"
 #include "base/sys_string_conversions.h"
 
@@ -55,7 +56,8 @@ void SysInfo::OperatingSystemVersionNumbers(int32* major_version,
 int64 SysInfo::AmountOfPhysicalMemory() {
   struct host_basic_info hostinfo;
   mach_msg_type_number_t count = HOST_BASIC_INFO_COUNT;
-  int result = host_info(mach_host_self(),
+  base::mac::ScopedMachPort host(mach_host_self());
+  int result = host_info(host,
                          HOST_BASIC_INFO,
                          reinterpret_cast<host_info_t>(&hostinfo),
                          &count);