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

components/tracing/process_metrics_memory_dump_provider.h

Index: components/tracing/process_metrics_memory_dump_provider.h
diff --git a/components/tracing/process_metrics_memory_dump_provider.h b/components/tracing/process_metrics_memory_dump_provider.h
new file mode 100644
index 0000000000000000000000000000000000000000..b002d10fe269661e7d1c3fc77d07c77f4d5f5412
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+++ b/components/tracing/process_metrics_memory_dump_provider.h
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+// 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_PROCESS_MEMORY_METRICS_DUMP_PROVIDER_H_
+#define COMPONENTS_TRACING_PROCESS_MEMORY_METRICS_DUMP_PROVIDER_H_
+
+#include "base/gtest_prod_util.h"
+#include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/process/process_handle.h"
+#include "base/trace_event/memory_dump_provider.h"
+#include "build/build_config.h"
+#include "components/tracing/tracing_export.h"
+
+namespace base {
+class ProcessMetrics;
+}
+
+namespace tracing {
+
+// Dump provider which collects process-wide memory stats.
+class TRACING_EXPORT ProcessMetricsMemoryDumpProvider
+    : public base::trace_event::MemoryDumpProvider {
+ 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;
+
+ private:
+  FRIEND_TEST_ALL_PREFIXES(ProcessMetricsMemoryDumpProviderTest,
+                           ParseProcSmaps);
+  FRIEND_TEST_ALL_PREFIXES(ProcessMetricsMemoryDumpProviderTest, DumpRSS);
+
+  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;
+#endif
+
+  base::ProcessId process_;
+  scoped_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_PROCESS_MEMORY_METRICS_DUMP_PROVIDER_H_