Fill in PlatformPrivateFootprint on Linux

components/tracing/common/process_metrics_memory_dump_provider.h

 // Copyright 2015 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.
 
 #ifndef COMPONENTS_TRACING_COMMON_PROCESS_MEMORY_METRICS_DUMP_PROVIDER_H_
 #define COMPONENTS_TRACING_COMMON_PROCESS_MEMORY_METRICS_DUMP_PROVIDER_H_
 
 #include <memory>
 
 #include "base/files/scoped_file.h"
@@ skipping 57 matching lines @@
                              base::trace_event::ProcessMemoryDump* pmd);
 
   static uint64_t rss_bytes_for_testing;
   static FactoryFunction factory_for_testing;
 
 #if defined(OS_LINUX) || defined(OS_ANDROID)
   static FILE* proc_smaps_for_testing;
   static int fast_polling_statm_fd_for_testing;
 
   base::ScopedFD fast_polling_statm_fd_;
+
+  base::ScopedFD OpenStatm();
 #endif
 
   base::ProcessId process_;
   std::unique_ptr<base::ProcessMetrics> process_metrics_;
 
   // The peak may not be resettable on all the processes if the linux kernel is
   // older than http://bit.ly/reset_rss or only on child processes if yama LSM
   // sandbox is enabled.
   bool is_rss_peak_resettable_;
 
   DISALLOW_COPY_AND_ASSIGN(ProcessMetricsMemoryDumpProvider);
 };
 
 }  // namespace tracing
 
 #endif  // COMPONENTS_TRACING_COMMON_PROCESS_MEMORY_METRICS_DUMP_PROVIDER_H_