[tracing] Dump child processes' memory metrics in browser

components/tracing/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 BASE_TRACE_EVENT_PROCESS_MEMORY_MAPS_DUMP_PROVIDER_H_
+#define BASE_TRACE_EVENT_PROCESS_MEMORY_MAPS_DUMP_PROVIDER_H_
+
+#include "base/gtest_prod_util.h"
+#include "base/macros.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::kNullProcessHandle to register for current process.
+  static void RegisterForProcess(base::ProcessHandle process);

[Primiano Tucci (use gerrit), 2015/12/14 10:52:21]

What is the rationale for passing ProcessHandle w.r.t. ProcessId? In the code
looks like you just need the ProcessId (which, btw, on Linux/Android happens to
be the same thing)

[ssid, 2016/01/04 20:54:38]

Hm the CreateProcessMetrics takes ProcessHandle and ProcessId.

+  static void UnregisterForProcess(base::ProcessHandle 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::ProcessHandle process);
+
+  void DumpProcessTotals(const base::trace_event::MemoryDumpArgs& args,
+                         base::trace_event::ProcessMemoryDump* pmd);
+  void DumpProcessMemoryMaps(const base::trace_event::MemoryDumpArgs& args,
+                             base::trace_event::ProcessMemoryDump* pmd);
+
+  static uint64 rss_bytes_for_testing;
+
+#if defined(OS_LINUX) || defined(OS_ANDROID)
+  static FILE* proc_smaps_for_testing;
+#endif
+
+  base::ProcessHandle process_;
+  scoped_ptr<base::ProcessMetrics> process_metrics_;
+
+  DISALLOW_COPY_AND_ASSIGN(ProcessMetricsMemoryDumpProvider);
+};
+
+}  // namespace tracing
+
+#endif  // BASE_TRACE_EVENT_PROCESS_MEMORY_MAPS_DUMP_PROVIDER_H_