[memory-infra] Implement PollFastMemoryTotal in ProcessMetricsMemoryDumpProvider.

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/gtest_prod_util.h"
@@ skipping 15 matching lines @@
  public:
   // Pass base::kNullProcessId to register for current process.
   static void RegisterForProcess(base::ProcessId process);
   static void UnregisterForProcess(base::ProcessId process);
 
   ~ProcessMetricsMemoryDumpProvider() override;
 
   // MemoryDumpProvider implementation.
   bool OnMemoryDump(const base::trace_event::MemoryDumpArgs& args,
                     base::trace_event::ProcessMemoryDump* pmd) override;
+  void PollFastMemoryTotal(uint64_t* memory_total) override;
+  void SetFastMemoryPollingEnabled(bool enabled) override;
 
  private:
   FRIEND_TEST_ALL_PREFIXES(ProcessMetricsMemoryDumpProviderTest,
                            ParseProcSmaps);
   FRIEND_TEST_ALL_PREFIXES(ProcessMetricsMemoryDumpProviderTest, DumpRSS);
+  FRIEND_TEST_ALL_PREFIXES(ProcessMetricsMemoryDumpProviderTest,
+                           TestPollFastMemoryTotal);
 
   ProcessMetricsMemoryDumpProvider(base::ProcessId process);
 
   bool DumpProcessTotals(const base::trace_event::MemoryDumpArgs& args,
                          base::trace_event::ProcessMemoryDump* pmd);
   bool DumpProcessMemoryMaps(const base::trace_event::MemoryDumpArgs& args,
                              base::trace_event::ProcessMemoryDump* pmd);
 
   static uint64_t rss_bytes_for_testing;
 
 #if defined(OS_LINUX) || defined(OS_ANDROID)
   static FILE* proc_smaps_for_testing;
+  static int fast_polling_statm_fd_for_testing;
+
+  int fast_polling_statm_fd_;

[Primiano Tucci (use gerrit), 2016/12/16 11:50:40]

I'm sorry I realized only now. This should be a base::ScopedFD, it's safer
w.r.t. risking of leaking fds.

[ssid, 2016/12/16 19:48:44]

Done.

 #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_