Reland of [tracing] Dump child processes' memory metrics in browser

base/trace_event/process_memory_totals_dump_provider.cc

Index: base/trace_event/process_memory_totals_dump_provider.cc
diff --git a/base/trace_event/process_memory_totals_dump_provider.cc b/base/trace_event/process_memory_totals_dump_provider.cc
deleted file mode 100644
index 1713ebf0bc99edd9b964bf66af8c2bfd8fd354b8..0000000000000000000000000000000000000000
--- a/base/trace_event/process_memory_totals_dump_provider.cc
+++ /dev/null
@@ -1,92 +0,0 @@
-// 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.
-
-#include "base/trace_event/process_memory_totals_dump_provider.h"
-
-#include <stddef.h>
-
-#include "base/process/process_metrics.h"
-#include "base/trace_event/process_memory_dump.h"
-#include "base/trace_event/process_memory_totals.h"
-#include "build/build_config.h"
-
-#if defined(OS_LINUX) || defined(OS_ANDROID)
-#include <fcntl.h>
-
-#include "base/files/file_util.h"
-
-namespace {
-bool kernel_supports_rss_peak_reset = true;
-const char kClearPeakRssCommand[] = "5";
-}
-#endif
-
-namespace base {
-namespace trace_event {
-
-// static
-uint64_t ProcessMemoryTotalsDumpProvider::rss_bytes_for_testing = 0;
-
-// static
-ProcessMemoryTotalsDumpProvider*
-ProcessMemoryTotalsDumpProvider::GetInstance() {
-  return Singleton<
-      ProcessMemoryTotalsDumpProvider,
-      LeakySingletonTraits<ProcessMemoryTotalsDumpProvider>>::get();
-}
-
-ProcessMemoryTotalsDumpProvider::ProcessMemoryTotalsDumpProvider()
-    : process_metrics_(ProcessMetrics::CreateCurrentProcessMetrics()) {}
-
-ProcessMemoryTotalsDumpProvider::~ProcessMemoryTotalsDumpProvider() {
-}
-
-// Called at trace dump point time. Creates a snapshot the memory counters for
-// the current process.
-bool ProcessMemoryTotalsDumpProvider::OnMemoryDump(const MemoryDumpArgs& args,
-                                                   ProcessMemoryDump* pmd) {
-  const uint64_t rss_bytes = rss_bytes_for_testing
-                                 ? rss_bytes_for_testing
-                                 : process_metrics_->GetWorkingSetSize();
-
-  uint64_t peak_rss_bytes = 0;
-
-#if !defined(OS_IOS)
-  peak_rss_bytes = process_metrics_->GetPeakWorkingSetSize();
-#if defined(OS_LINUX) || defined(OS_ANDROID)
-  if (kernel_supports_rss_peak_reset) {
-    // TODO(ssid): Fix crbug.com/461788 to write to the file from sandboxed
-    // processes.
-    int clear_refs_fd = open("/proc/self/clear_refs", O_WRONLY);
-    if (clear_refs_fd > 0 &&
-        WriteFileDescriptor(clear_refs_fd, kClearPeakRssCommand,
-                            sizeof(kClearPeakRssCommand))) {
-      pmd->process_totals()->set_is_peak_rss_resetable(true);
-    } else {
-      kernel_supports_rss_peak_reset = false;
-    }
-    close(clear_refs_fd);
-  }
-#elif defined(OS_MACOSX)
-  size_t private_bytes;
-  bool res = process_metrics_->GetMemoryBytes(&private_bytes,
-                                              nullptr /* shared_bytes */);
-  if (res) {
-    pmd->process_totals()->SetExtraFieldInBytes("private_bytes", private_bytes);
-  }
-#endif  // defined(OS_LINUX) || defined(OS_ANDROID)
-#endif  // !defined(OS_IOS)
-
-  if (rss_bytes > 0) {
-    pmd->process_totals()->set_resident_set_bytes(rss_bytes);
-    pmd->process_totals()->set_peak_resident_set_bytes(peak_rss_bytes);
-    pmd->set_has_process_totals();
-    return true;
-  }
-
-  return false;
-}
-
-}  // namespace trace_event
-}  // namespace base