[Fuchsia] Calculate RSS using new task stat fields

runtime/bin/process_fuchsia.cc

 // Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #if !defined(DART_IO_DISABLED)
 
 #include "platform/globals.h"
 #if defined(HOST_OS_FUCHSIA)
 
 #include "bin/process.h"
@@ skipping 423 matching lines @@
 int64_t Process::CurrentRSS() {
   mx_info_task_stats_t task_stats;
   mx_handle_t process = mx_process_self();
   mx_status_t status = mx_object_get_info(
       process, MX_INFO_TASK_STATS, &task_stats, sizeof(task_stats), NULL, NULL);
   if (status != NO_ERROR) {
     // TODO(zra): Translate this to a Unix errno.
     errno = status;
     return -1;
   }
-  return task_stats.mem_committed_bytes;
+  return task_stats.mem_private_bytes + task_stats.mem_shared_bytes;
 }
 
 
 int64_t Process::MaxRSS() {
   // There is currently no way to get the high watermark value on Fuchsia, so
   // just return the current RSS value.
   return CurrentRSS();
 }
 
 
@@ skipping 381 matching lines @@
 
 void Process::ClearSignalHandler(intptr_t signal) {
 }
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // defined(HOST_OS_FUCHSIA)
 
 #endif  // !defined(DART_IO_DISABLED)