[tracing] Add a dump provider to dump process memory totals.

base/trace_event/process_memory_totals_dump_provider.cc

+// 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 "base/process/process_metrics.h"
+#include "base/trace_event/process_memory_dump.h"
+#include "base/trace_event/process_memory_totals.h"
+
+namespace base {
+namespace trace_event {
+
+// static
+ProcessMemoryTotalsDumpProvider*
+ProcessMemoryTotalsDumpProvider::GetInstance() {
+  return Singleton<
+      ProcessMemoryTotalsDumpProvider,
+      LeakySingletonTraits<ProcessMemoryTotalsDumpProvider>>::get();
+}
+
+ProcessMemoryTotalsDumpProvider::ProcessMemoryTotalsDumpProvider()
+    : process_metrics_(
+          ProcessMetrics::CreateProcessMetrics(GetCurrentProcessHandle())) {
+}
+
+ProcessMemoryTotalsDumpProvider::~ProcessMemoryTotalsDumpProvider() {
+}
+
+// Called at trace dump point time. Creates a snapshot the memory counters for
+// the current process.
+void ProcessMemoryTotalsDumpProvider::DumpInto(ProcessMemoryDump* pmd) {
+  const uint64 rss_bytes = process_metrics_->GetWorkingSetSize();
+  pmd->process_totals()->set_resident_set_bytes(rss_bytes);
+  pmd->set_has_process_totals();
+}
+
+}  // namespace trace_event
+}  // namespace base