mac: Fix calulation for number of resident pages in a process.

base/process/process_metrics.h

 // Copyright (c) 2013 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.
 
 // This file contains routines for gathering resource statistics for processes
 // running on the system.
 
 #ifndef BASE_PROCESS_PROCESS_METRICS_H_
 #define BASE_PROCESS_PROCESS_METRICS_H_
 
@@ skipping 118 matching lines @@
   size_t GetPeakPagefileUsage() const;
   // Returns the current working set size, in bytes.  On Linux, this returns
   // the resident set size.
   size_t GetWorkingSetSize() const;
   // Returns the peak working set size, in bytes.
   size_t GetPeakWorkingSetSize() const;
   // Returns private and sharedusage, in bytes. Private bytes is the amount of
   // memory currently allocated to a process that cannot be shared. Returns
   // false on platform specific error conditions.  Note: |private_bytes|
   // returns 0 on unsupported OSes: prior to XP SP2.
-  bool GetMemoryBytes(size_t* private_bytes,
-                      size_t* shared_bytes);
+  bool GetMemoryBytes(size_t* private_bytes, size_t* shared_bytes) const;
   // Fills a CommittedKBytes with both resident and paged
   // memory usage as per definition of CommittedBytes.
   void GetCommittedKBytes(CommittedKBytes* usage) const;
   // Fills a WorkingSetKBytes containing resident private and shared memory
   // usage in bytes, as per definition of WorkingSetBytes. Note that this
   // function is somewhat expensive on Windows (a few ms per process).
   bool GetWorkingSetKBytes(WorkingSetKBytes* ws_usage) const;
   // Computes pss (proportional set size) of a process. Note that this
   // function is somewhat expensive on Windows (a few ms per process).
   bool GetProportionalSetSizeBytes(uint64_t* pss_bytes) const;
@@ skipping 279 matching lines @@
   SystemDiskInfo disk_info_;
 #endif
 #if defined(OS_CHROMEOS)
   SwapInfo swap_info_;
 #endif
 };
 
 }  // namespace base
 
 #endif  // BASE_PROCESS_PROCESS_METRICS_H_