Report utility process JS memory in task manager.

chrome/browser/process_resource_usage.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 CHROME_BROWSER_PROCESS_RESOURCE_USAGE_H_
+#define CHROME_BROWSER_PROCESS_RESOURCE_USAGE_H_
+
+#include "base/basictypes.h"
+#include "base/threading/thread_checker.h"
+#include "chrome/common/resource_usage_reporter.mojom.h"
+
+// Provides resource usage information about a child process.
+//
+// This is a wrapper around the ResourceUsageReporter Mojo service that exposes
+// information about resources used by a child process. Currently, this is only
+// V8 memory usage, but could be expanded to include other resources such as web
+// cache. This is intended for status viewers such as the task manager and
+// about://memory-internals.

[jam, 2015/05/12 16:12:23]

is someone tasked to make about:memory-internals to switch to it? perhaps until
that's done, this class should live in task_manager directory?

[Anand Mistry (off Chromium), 2015/05/13 00:42:11]

Yes, me. I have another CL in progress that switches the renderer to use this
and also switches memory-internals.

+//
+// To create:
+// 1. Obtain a ResourceUsageReporter connection using the child process's
+//    service registry. i.e:
+//    ResourceUsageReporterPtr service;
+//    process->GetServiceRegistry()->ConnectToRemoteService(&service);
+// 2. If needed, the connection can be passed to another thread using
+//    ResourceUsageReporterPtr::PassInterface().
+// 3. Pass the service to the constructor.
+//
+// Note: ProcessResourceUsage is thread-hostile and must live on a single
+// thread.
+class ProcessResourceUsage {
+ public:
+  // Must be called from the same thread that created |service|.
+  explicit ProcessResourceUsage(ResourceUsageReporterPtr service);
+  ~ProcessResourceUsage();
+
+  // Refresh the resource usage information.
+  void Refresh();
+
+  // Get V8 memory usage information.
+  bool ReportsV8MemoryStats() const;
+  size_t GetV8MemoryAllocated() const;
+  size_t GetV8MemoryUsed() const;
+
+ private:
+  // Mojo IPC callback.
+  void OnRefreshDone(ResourceUsageDataPtr data);
+
+  ResourceUsageReporterPtr service_;
+  bool update_in_progress_;
+
+  ResourceUsageDataPtr stats_;
+
+  base::ThreadChecker thread_checker_;
+
+  DISALLOW_COPY_AND_ASSIGN(ProcessResourceUsage);
+};
+
+#endif  // CHROME_BROWSER_PROCESS_RESOURCE_USAGE_H_