Add empty implementation of GetSystemMemoryInfo for IOS.

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 229 matching lines @@
 // Sets the file descriptor soft limit to |max_descriptors| or the OS hard
 // limit, whichever is lower.
 BASE_EXPORT void SetFdLimit(unsigned int max_descriptors);
 #endif  // defined(OS_POSIX)
 
 #if defined(OS_WIN) || defined(OS_MACOSX) || defined(OS_LINUX) || \
     defined(OS_ANDROID)
 // Data about system-wide memory consumption. Values are in KB. Available on
 // Windows, Mac, Linux, Android and Chrome OS.
 //
-// Total/free memory are available on all platforms. Total/free swap memory are
-// available on all platforms except on Mac. Buffers/cached/active_anon/
-// inactive_anon/active_file/inactive_file/dirty/pswpin/pswpout/pgmajfault are
-// available on Linux/Android/Chrome OS. Shmem/slab/gem_objects/gem_size are
-// Chrome OS specific.
+// Total/free memory are available on all platforms that implement
+// GetSystemMemoryInfo(). Total/free swap memory are available on all platforms
+// except on Mac. Buffers/cached/active_anon/inactive_anon/active_file/
+// inactive_file/dirty/pswpin/pswpout/pgmajfault are available on
+// Linux/Android/Chrome OS. Shmem/slab/gem_objects/gem_size are Chrome OS only.
 struct BASE_EXPORT SystemMemoryInfoKB {
   SystemMemoryInfoKB();
 
   // Serializes the platform specific fields to value.
   scoped_ptr<Value> ToValue() const;
 
   int total;
   int free;
 
 #if !defined(OS_MACOSX)
@@ skipping 138 matching lines @@
   SystemDiskInfo disk_info_;
 #endif
 #if defined(OS_CHROMEOS)
   SwapInfo swap_info_;
 #endif
 };
 
 }  // namespace base
 
 #endif  // BASE_PROCESS_PROCESS_METRICS_H_