[tracing] Dump child processes' memory metrics in browser

components/tracing/process_metrics_memory_dump_manager.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_PROCESS_METRICS_MEMORY_DUMP_MANAGER_H_
+#define COMPONENTS_TRACING_PROCESS_METRICS_MEMORY_DUMP_MANAGER_H_
+
+#include "base/containers/scoped_ptr_map.h"
+#include "base/macros.h"
+#include "base/memory/singleton.h"
+#include "base/process/process_handle.h"
+#include "components/tracing/tracing_export.h"
+
+namespace tracing {
+
+class ProcessMetricsMemoryDumpProvider;
+
+// Creates and registeres the ProcessMetricsMemoryDumpProvider for current
+// process and its children. Controls the lifetime of the providers.
+class TRACING_EXPORT ProcessMetricsMemoryDumpManager {

[Primiano Tucci (use gerrit), 2015/11/17 10:44:12]

hmm we have way too many managers in memory-infra. I understand the need of
RegisterFOrProcess, but can we just move that into the
ProcessMetricsMemoryDumpProvider itself (as static methods)?

[ssid, 2015/11/17 11:13:07]

This would mean that there is a global std::map (not ScopedPtrMap) of the
pointers to dump providers in anonymous namespace. Also, this map is stored as
pointer or a lazy instance. Manager with scoped_ptrs sounded better than that.
The reason for the manager is to store the providers, not registration. WDYT?

[ssid, 2015/11/17 13:55:06]

Done.

+ public:
+  static ProcessMetricsMemoryDumpManager* GetInstance();
+
+  // Pass base::kNullProcessHandle to register for current process.
+  void RegisterForProcess(base::ProcessHandle process);
+  void UnregisterForProcess(base::ProcessHandle process);
+
+ private:
+  friend struct base::DefaultSingletonTraits<ProcessMetricsMemoryDumpManager>;
+
+  using ProcessMetricsDumpProvidersMap =
+      base::ScopedPtrMap<base::ProcessHandle,
+                         scoped_ptr<ProcessMetricsMemoryDumpProvider>>;
+
+  ProcessMetricsMemoryDumpManager();
+  ~ProcessMetricsMemoryDumpManager();
+
+  ProcessMetricsDumpProvidersMap process_metrics_providers_map_;
+
+  DISALLOW_COPY_AND_ASSIGN(ProcessMetricsMemoryDumpManager);
+};
+
+}  // namespace tracing
+
+#endif  // COMPONENTS_TRACING_PROCESS_METRICS_MEMORY_DUMP_MANAGER_H_