Report utility process JS memory in task manager.

content/public/browser/child_process_data.h

 // Copyright (c) 2012 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 CONTENT_PUBLIC_BROWSER_CHILD_PROCESS_DATA_H_
 #define CONTENT_PUBLIC_BROWSER_CHILD_PROCESS_DATA_H_
 
+#include "base/memory/ref_counted.h"
 #include "base/process/process.h"
 #include "base/strings/string16.h"
 #include "content/common/content_export.h"
+#include "content/public/browser/process_resource_usage.h"
 
 namespace content {
 
 // Holds information about a child process.
-struct ChildProcessData {
+struct CONTENT_EXPORT ChildProcessData {
   // The type of the process.
   int process_type;
 
   // The name of the process.  i.e. for plugins it might be Flash, while for
   // for workers it might be the domain that it's from.
   base::string16 name;
 
   // The unique identifier for this child process. This identifier is NOT a
   // process ID, and will be unique for all types of child process for
   // one run of the browser.
   int id;
 
   // The handle to the process. May have value kNullProcessHandle if no process
   // exists - either because it hasn't been started yet or it's running in the
   // current process.
   base::ProcessHandle handle;
 
-  explicit ChildProcessData(int process_type)
-      : process_type(process_type), id(0), handle(base::kNullProcessHandle) {
-  }
+  // Resource usage reporter to obtain certain resource stats such as JS memory
+  // usage. May be null.
+  scoped_refptr<ProcessResourceUsage> process_resource_usage;

[ncarter (slow), 2015/05/01 21:16:52]

As implemented, this modification does plumb the process_resource_usage
everywhere it needs to go, and effortlessly. But is it too much of a shortcut?
Does this member belong in this class?

This type, ChildProcessData, up until now has functioned as the signature/id of
the process: it's passed to every method of BrowserChildProcessObserver (process
creations and deletions alike); historically (ages ago) I think it was intended
for use as a map key. It's a struct, copyable, and those are usually reserved
for passing around plain data.

But here you're adding a scoped pointer to a stateful object that has a Refresh
method and whose values could change synchronously at any moment. That doesn't
feel like something that belongs in a copyable-identifier-struct-like to me.

Is there a way to implement this without adding a stateful object to
ChildProcessData? How much grosser is that?

[Anand Mistry (off Chromium), 2015/05/06 02:44:18]

Done. It requires more plumbing, but isn't as bad as I thought it would be. 

+
+  explicit ChildProcessData(int process_type);
+  ~ChildProcessData();
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_CHILD_PROCESS_DATA_H_